1951 lines
76 KiB
Python
1951 lines
76 KiB
Python
"""
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The main QuerySet implementation. This provides the public API for the ORM.
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"""
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from collections import deque, OrderedDict
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import copy
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import sys
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import warnings
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from django.conf import settings
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from django.core import exceptions
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from django.db import (connections, router, transaction, IntegrityError,
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DJANGO_VERSION_PICKLE_KEY)
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from django.db.models.constants import LOOKUP_SEP
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from django.db.models.fields import AutoField, Empty
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from django.db.models.query_utils import (Q, select_related_descend,
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deferred_class_factory, InvalidQuery)
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from django.db.models.deletion import Collector
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from django.db.models.sql.constants import CURSOR
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from django.db.models import sql
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from django.utils.functional import partition
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from django.utils import six
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from django.utils import timezone
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from django.utils.version import get_version
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# The maximum number (one less than the max to be precise) of results to fetch
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# in a get() query
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MAX_GET_RESULTS = 20
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# The maximum number of items to display in a QuerySet.__repr__
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REPR_OUTPUT_SIZE = 20
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# Pull into this namespace for backwards compatibility.
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EmptyResultSet = sql.EmptyResultSet
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def _pickle_queryset(class_bases, class_dict):
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"""
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Used by `__reduce__` to create the initial version of the `QuerySet` class
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onto which the output of `__getstate__` will be applied.
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See `__reduce__` for more details.
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"""
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new = Empty()
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new.__class__ = type(class_bases[0].__name__, class_bases, class_dict)
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return new
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class QuerySet(object):
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"""
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Represents a lazy database lookup for a set of objects.
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"""
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def __init__(self, model=None, query=None, using=None, hints=None):
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self.model = model
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self._db = using
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self._hints = hints or {}
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self.query = query or sql.Query(self.model)
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self._result_cache = None
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self._sticky_filter = False
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self._for_write = False
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self._prefetch_related_lookups = []
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self._prefetch_done = False
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self._known_related_objects = {} # {rel_field, {pk: rel_obj}}
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def as_manager(cls):
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# Address the circular dependency between `Queryset` and `Manager`.
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from django.db.models.manager import Manager
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return Manager.from_queryset(cls)()
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as_manager.queryset_only = True
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as_manager = classmethod(as_manager)
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########################
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# PYTHON MAGIC METHODS #
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########################
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def __deepcopy__(self, memo):
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"""
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Deep copy of a QuerySet doesn't populate the cache
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"""
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obj = self.__class__()
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for k, v in self.__dict__.items():
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if k == '_result_cache':
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obj.__dict__[k] = None
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else:
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obj.__dict__[k] = copy.deepcopy(v, memo)
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return obj
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def __getstate__(self):
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"""
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Allows the QuerySet to be pickled.
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"""
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# Force the cache to be fully populated.
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self._fetch_all()
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obj_dict = self.__dict__.copy()
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obj_dict[DJANGO_VERSION_PICKLE_KEY] = get_version()
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return obj_dict
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def __setstate__(self, state):
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msg = None
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pickled_version = state.get(DJANGO_VERSION_PICKLE_KEY)
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if pickled_version:
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current_version = get_version()
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if current_version != pickled_version:
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msg = ("Pickled queryset instance's Django version %s does"
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" not match the current version %s."
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% (pickled_version, current_version))
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else:
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msg = "Pickled queryset instance's Django version is not specified."
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if msg:
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warnings.warn(msg, RuntimeWarning, stacklevel=2)
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self.__dict__.update(state)
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def __reduce__(self):
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"""
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Used by pickle to deal with the types that we create dynamically when
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specialized queryset such as `ValuesQuerySet` are used in conjunction
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with querysets that are *subclasses* of `QuerySet`.
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See `_clone` implementation for more details.
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"""
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if hasattr(self, '_specialized_queryset_class'):
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class_bases = (
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self._specialized_queryset_class,
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self._base_queryset_class,
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)
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class_dict = {
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'_specialized_queryset_class': self._specialized_queryset_class,
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'_base_queryset_class': self._base_queryset_class,
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}
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return _pickle_queryset, (class_bases, class_dict), self.__getstate__()
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return super(QuerySet, self).__reduce__()
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def __repr__(self):
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data = list(self[:REPR_OUTPUT_SIZE + 1])
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if len(data) > REPR_OUTPUT_SIZE:
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data[-1] = "...(remaining elements truncated)..."
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return repr(data)
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def __len__(self):
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self._fetch_all()
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return len(self._result_cache)
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def __iter__(self):
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"""
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The queryset iterator protocol uses three nested iterators in the
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default case:
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1. sql.compiler:execute_sql()
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- Returns 100 rows at time (constants.GET_ITERATOR_CHUNK_SIZE)
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using cursor.fetchmany(). This part is responsible for
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doing some column masking, and returning the rows in chunks.
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2. sql/compiler.results_iter()
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- Returns one row at time. At this point the rows are still just
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tuples. In some cases the return values are converted to
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Python values at this location (see resolve_columns(),
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resolve_aggregate()).
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3. self.iterator()
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- Responsible for turning the rows into model objects.
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"""
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self._fetch_all()
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return iter(self._result_cache)
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def __bool__(self):
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self._fetch_all()
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return bool(self._result_cache)
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def __nonzero__(self): # Python 2 compatibility
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return type(self).__bool__(self)
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def __getitem__(self, k):
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"""
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Retrieves an item or slice from the set of results.
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"""
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if not isinstance(k, (slice,) + six.integer_types):
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raise TypeError
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assert ((not isinstance(k, slice) and (k >= 0)) or
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(isinstance(k, slice) and (k.start is None or k.start >= 0) and
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(k.stop is None or k.stop >= 0))), \
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"Negative indexing is not supported."
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if self._result_cache is not None:
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return self._result_cache[k]
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if isinstance(k, slice):
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qs = self._clone()
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if k.start is not None:
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start = int(k.start)
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else:
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start = None
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if k.stop is not None:
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stop = int(k.stop)
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else:
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stop = None
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qs.query.set_limits(start, stop)
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return list(qs)[::k.step] if k.step else qs
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qs = self._clone()
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qs.query.set_limits(k, k + 1)
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return list(qs)[0]
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def __and__(self, other):
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self._merge_sanity_check(other)
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if isinstance(other, EmptyQuerySet):
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return other
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if isinstance(self, EmptyQuerySet):
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return self
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combined = self._clone()
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combined._merge_known_related_objects(other)
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combined.query.combine(other.query, sql.AND)
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return combined
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def __or__(self, other):
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self._merge_sanity_check(other)
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if isinstance(self, EmptyQuerySet):
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return other
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if isinstance(other, EmptyQuerySet):
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return self
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combined = self._clone()
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combined._merge_known_related_objects(other)
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combined.query.combine(other.query, sql.OR)
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return combined
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####################################
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# METHODS THAT DO DATABASE QUERIES #
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####################################
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def iterator(self):
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"""
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An iterator over the results from applying this QuerySet to the
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database.
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"""
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fill_cache = False
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if connections[self.db].features.supports_select_related:
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fill_cache = self.query.select_related
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if isinstance(fill_cache, dict):
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requested = fill_cache
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else:
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requested = None
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max_depth = self.query.max_depth
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extra_select = list(self.query.extra_select)
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aggregate_select = list(self.query.aggregate_select)
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only_load = self.query.get_loaded_field_names()
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fields = self.model._meta.concrete_fields
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load_fields = []
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# If only/defer clauses have been specified,
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# build the list of fields that are to be loaded.
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if only_load:
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for field, model in self.model._meta.get_concrete_fields_with_model():
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if model is None:
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model = self.model
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try:
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if field.name in only_load[model]:
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# Add a field that has been explicitly included
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load_fields.append(field.name)
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except KeyError:
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# Model wasn't explicitly listed in the only_load table
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# Therefore, we need to load all fields from this model
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load_fields.append(field.name)
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skip = None
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if load_fields:
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# Some fields have been deferred, so we have to initialize
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# via keyword arguments.
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skip = set()
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init_list = []
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for field in fields:
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if field.name not in load_fields:
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skip.add(field.attname)
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else:
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init_list.append(field.attname)
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model_cls = deferred_class_factory(self.model, skip)
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else:
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model_cls = self.model
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init_list = [f.attname for f in fields]
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# Cache db and model outside the loop
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db = self.db
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compiler = self.query.get_compiler(using=db)
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index_start = len(extra_select)
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aggregate_start = index_start + len(init_list)
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if fill_cache:
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klass_info = get_klass_info(model_cls, max_depth=max_depth,
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requested=requested, only_load=only_load)
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for row in compiler.results_iter():
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if fill_cache:
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obj, _ = get_cached_row(row, index_start, db, klass_info,
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offset=len(aggregate_select))
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else:
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obj = model_cls.from_db(db, init_list, row[index_start:aggregate_start])
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if extra_select:
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for i, k in enumerate(extra_select):
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setattr(obj, k, row[i])
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# Add the aggregates to the model
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if aggregate_select:
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for i, aggregate in enumerate(aggregate_select):
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setattr(obj, aggregate, row[i + aggregate_start])
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# Add the known related objects to the model, if there are any
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if self._known_related_objects:
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for field, rel_objs in self._known_related_objects.items():
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# Avoid overwriting objects loaded e.g. by select_related
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if hasattr(obj, field.get_cache_name()):
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continue
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pk = getattr(obj, field.get_attname())
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try:
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rel_obj = rel_objs[pk]
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except KeyError:
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pass # may happen in qs1 | qs2 scenarios
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else:
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setattr(obj, field.name, rel_obj)
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yield obj
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def aggregate(self, *args, **kwargs):
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"""
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Returns a dictionary containing the calculations (aggregation)
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over the current queryset
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If args is present the expression is passed as a kwarg using
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the Aggregate object's default alias.
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"""
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if self.query.distinct_fields:
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raise NotImplementedError("aggregate() + distinct(fields) not implemented.")
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for arg in args:
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kwargs[arg.default_alias] = arg
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query = self.query.clone()
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force_subq = query.low_mark != 0 or query.high_mark is not None
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for (alias, aggregate_expr) in kwargs.items():
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query.add_aggregate(aggregate_expr, self.model, alias,
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is_summary=True)
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return query.get_aggregation(using=self.db, force_subq=force_subq)
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def count(self):
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"""
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Performs a SELECT COUNT() and returns the number of records as an
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integer.
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If the QuerySet is already fully cached this simply returns the length
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of the cached results set to avoid multiple SELECT COUNT(*) calls.
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"""
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if self._result_cache is not None:
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return len(self._result_cache)
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return self.query.get_count(using=self.db)
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def get(self, *args, **kwargs):
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"""
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Performs the query and returns a single object matching the given
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keyword arguments.
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"""
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clone = self.filter(*args, **kwargs)
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if self.query.can_filter():
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clone = clone.order_by()
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if (not clone.query.select_for_update or
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connections[self.db].features.supports_select_for_update_with_limit):
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clone = clone[:MAX_GET_RESULTS + 1]
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num = len(clone)
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if num == 1:
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return clone._result_cache[0]
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if not num:
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raise self.model.DoesNotExist(
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"%s matching query does not exist." %
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self.model._meta.object_name)
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raise self.model.MultipleObjectsReturned(
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"get() returned more than one %s -- it returned %s!" % (
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self.model._meta.object_name,
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num if num <= MAX_GET_RESULTS else 'more than %s' % MAX_GET_RESULTS
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)
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)
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def create(self, **kwargs):
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"""
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Creates a new object with the given kwargs, saving it to the database
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and returning the created object.
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"""
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obj = self.model(**kwargs)
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self._for_write = True
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obj.save(force_insert=True, using=self.db)
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return obj
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def bulk_create(self, objs, batch_size=None):
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"""
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Inserts each of the instances into the database. This does *not* call
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save() on each of the instances, does not send any pre/post save
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signals, and does not set the primary key attribute if it is an
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autoincrement field.
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"""
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# So this case is fun. When you bulk insert you don't get the primary
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# keys back (if it's an autoincrement), so you can't insert into the
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# child tables which references this. There are two workarounds, 1)
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# this could be implemented if you didn't have an autoincrement pk,
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# and 2) you could do it by doing O(n) normal inserts into the parent
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# tables to get the primary keys back, and then doing a single bulk
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# insert into the childmost table. Some databases might allow doing
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# this by using RETURNING clause for the insert query. We're punting
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# on these for now because they are relatively rare cases.
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assert batch_size is None or batch_size > 0
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if self.model._meta.parents:
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raise ValueError("Can't bulk create an inherited model")
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if not objs:
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return objs
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self._for_write = True
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connection = connections[self.db]
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fields = self.model._meta.local_concrete_fields
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with transaction.atomic(using=self.db, savepoint=False):
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if (connection.features.can_combine_inserts_with_and_without_auto_increment_pk
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and self.model._meta.has_auto_field):
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self._batched_insert(objs, fields, batch_size)
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else:
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objs_with_pk, objs_without_pk = partition(lambda o: o.pk is None, objs)
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if objs_with_pk:
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self._batched_insert(objs_with_pk, fields, batch_size)
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if objs_without_pk:
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fields = [f for f in fields if not isinstance(f, AutoField)]
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self._batched_insert(objs_without_pk, fields, batch_size)
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return objs
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def get_or_create(self, defaults=None, **kwargs):
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"""
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Looks up an object with the given kwargs, creating one if necessary.
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Returns a tuple of (object, created), where created is a boolean
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specifying whether an object was created.
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"""
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lookup, params = self._extract_model_params(defaults, **kwargs)
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self._for_write = True
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try:
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return self.get(**lookup), False
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except self.model.DoesNotExist:
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return self._create_object_from_params(lookup, params)
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def update_or_create(self, defaults=None, **kwargs):
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"""
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Looks up an object with the given kwargs, updating one with defaults
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if it exists, otherwise creates a new one.
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Returns a tuple (object, created), where created is a boolean
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specifying whether an object was created.
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"""
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defaults = defaults or {}
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lookup, params = self._extract_model_params(defaults, **kwargs)
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self._for_write = True
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try:
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obj = self.get(**lookup)
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except self.model.DoesNotExist:
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obj, created = self._create_object_from_params(lookup, params)
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if created:
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return obj, created
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for k, v in six.iteritems(defaults):
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setattr(obj, k, v)
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with transaction.atomic(using=self.db, savepoint=False):
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obj.save(using=self.db)
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return obj, False
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def _create_object_from_params(self, lookup, params):
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"""
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Tries to create an object using passed params.
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Used by get_or_create and update_or_create
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"""
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try:
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with transaction.atomic(using=self.db):
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obj = self.create(**params)
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return obj, True
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except IntegrityError:
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exc_info = sys.exc_info()
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try:
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return self.get(**lookup), False
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except self.model.DoesNotExist:
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pass
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six.reraise(*exc_info)
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def _extract_model_params(self, defaults, **kwargs):
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"""
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Prepares `lookup` (kwargs that are valid model attributes), `params`
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(for creating a model instance) based on given kwargs; for use by
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get_or_create and update_or_create.
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"""
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defaults = defaults or {}
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lookup = kwargs.copy()
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for f in self.model._meta.fields:
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if f.attname in lookup:
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lookup[f.name] = lookup.pop(f.attname)
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params = dict((k, v) for k, v in kwargs.items() if LOOKUP_SEP not in k)
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params.update(defaults)
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return lookup, params
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def _earliest_or_latest(self, field_name=None, direction="-"):
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"""
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Returns the latest object, according to the model's
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'get_latest_by' option or optional given field_name.
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"""
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order_by = field_name or getattr(self.model._meta, 'get_latest_by')
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assert bool(order_by), "earliest() and latest() require either a "\
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"field_name parameter or 'get_latest_by' in the model"
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assert self.query.can_filter(), \
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"Cannot change a query once a slice has been taken."
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obj = self._clone()
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obj.query.set_limits(high=1)
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obj.query.clear_ordering(force_empty=True)
|
|
obj.query.add_ordering('%s%s' % (direction, order_by))
|
|
return obj.get()
|
|
|
|
def earliest(self, field_name=None):
|
|
return self._earliest_or_latest(field_name=field_name, direction="")
|
|
|
|
def latest(self, field_name=None):
|
|
return self._earliest_or_latest(field_name=field_name, direction="-")
|
|
|
|
def first(self):
|
|
"""
|
|
Returns the first object of a query, returns None if no match is found.
|
|
"""
|
|
objects = list((self if self.ordered else self.order_by('pk'))[:1])
|
|
if objects:
|
|
return objects[0]
|
|
return None
|
|
|
|
def last(self):
|
|
"""
|
|
Returns the last object of a query, returns None if no match is found.
|
|
"""
|
|
objects = list((self.reverse() if self.ordered else self.order_by('-pk'))[:1])
|
|
if objects:
|
|
return objects[0]
|
|
return None
|
|
|
|
def in_bulk(self, id_list):
|
|
"""
|
|
Returns a dictionary mapping each of the given IDs to the object with
|
|
that ID.
|
|
"""
|
|
assert self.query.can_filter(), \
|
|
"Cannot use 'limit' or 'offset' with in_bulk"
|
|
if not id_list:
|
|
return {}
|
|
qs = self.filter(pk__in=id_list).order_by()
|
|
return dict((obj._get_pk_val(), obj) for obj in qs)
|
|
|
|
def delete(self):
|
|
"""
|
|
Deletes the records in the current QuerySet.
|
|
"""
|
|
assert self.query.can_filter(), \
|
|
"Cannot use 'limit' or 'offset' with delete."
|
|
|
|
del_query = self._clone()
|
|
|
|
# The delete is actually 2 queries - one to find related objects,
|
|
# and one to delete. Make sure that the discovery of related
|
|
# objects is performed on the same database as the deletion.
|
|
del_query._for_write = True
|
|
|
|
# Disable non-supported fields.
|
|
del_query.query.select_for_update = False
|
|
del_query.query.select_related = False
|
|
del_query.query.clear_ordering(force_empty=True)
|
|
|
|
collector = Collector(using=del_query.db)
|
|
collector.collect(del_query)
|
|
collector.delete()
|
|
|
|
# Clear the result cache, in case this QuerySet gets reused.
|
|
self._result_cache = None
|
|
delete.alters_data = True
|
|
delete.queryset_only = True
|
|
|
|
def _raw_delete(self, using):
|
|
"""
|
|
Deletes objects found from the given queryset in single direct SQL
|
|
query. No signals are sent, and there is no protection for cascades.
|
|
"""
|
|
sql.DeleteQuery(self.model).delete_qs(self, using)
|
|
_raw_delete.alters_data = True
|
|
|
|
def update(self, **kwargs):
|
|
"""
|
|
Updates all elements in the current QuerySet, setting all the given
|
|
fields to the appropriate values.
|
|
"""
|
|
assert self.query.can_filter(), \
|
|
"Cannot update a query once a slice has been taken."
|
|
self._for_write = True
|
|
query = self.query.clone(sql.UpdateQuery)
|
|
query.add_update_values(kwargs)
|
|
with transaction.atomic(using=self.db, savepoint=False):
|
|
rows = query.get_compiler(self.db).execute_sql(CURSOR)
|
|
self._result_cache = None
|
|
return rows
|
|
update.alters_data = True
|
|
|
|
def _update(self, values):
|
|
"""
|
|
A version of update that accepts field objects instead of field names.
|
|
Used primarily for model saving and not intended for use by general
|
|
code (it requires too much poking around at model internals to be
|
|
useful at that level).
|
|
"""
|
|
assert self.query.can_filter(), \
|
|
"Cannot update a query once a slice has been taken."
|
|
query = self.query.clone(sql.UpdateQuery)
|
|
query.add_update_fields(values)
|
|
self._result_cache = None
|
|
return query.get_compiler(self.db).execute_sql(CURSOR)
|
|
_update.alters_data = True
|
|
_update.queryset_only = False
|
|
|
|
def exists(self):
|
|
if self._result_cache is None:
|
|
return self.query.has_results(using=self.db)
|
|
return bool(self._result_cache)
|
|
|
|
def _prefetch_related_objects(self):
|
|
# This method can only be called once the result cache has been filled.
|
|
prefetch_related_objects(self._result_cache, self._prefetch_related_lookups)
|
|
self._prefetch_done = True
|
|
|
|
##################################################
|
|
# PUBLIC METHODS THAT RETURN A QUERYSET SUBCLASS #
|
|
##################################################
|
|
|
|
def raw(self, raw_query, params=None, translations=None, using=None):
|
|
if using is None:
|
|
using = self.db
|
|
return RawQuerySet(raw_query, model=self.model,
|
|
params=params, translations=translations,
|
|
using=using)
|
|
|
|
def values(self, *fields):
|
|
return self._clone(klass=ValuesQuerySet, setup=True, _fields=fields)
|
|
|
|
def values_list(self, *fields, **kwargs):
|
|
flat = kwargs.pop('flat', False)
|
|
if kwargs:
|
|
raise TypeError('Unexpected keyword arguments to values_list: %s'
|
|
% (list(kwargs),))
|
|
if flat and len(fields) > 1:
|
|
raise TypeError("'flat' is not valid when values_list is called with more than one field.")
|
|
return self._clone(klass=ValuesListQuerySet, setup=True, flat=flat,
|
|
_fields=fields)
|
|
|
|
def dates(self, field_name, kind, order='ASC'):
|
|
"""
|
|
Returns a list of date objects representing all available dates for
|
|
the given field_name, scoped to 'kind'.
|
|
"""
|
|
assert kind in ("year", "month", "day"), \
|
|
"'kind' must be one of 'year', 'month' or 'day'."
|
|
assert order in ('ASC', 'DESC'), \
|
|
"'order' must be either 'ASC' or 'DESC'."
|
|
return self._clone(klass=DateQuerySet, setup=True,
|
|
_field_name=field_name, _kind=kind, _order=order)
|
|
|
|
def datetimes(self, field_name, kind, order='ASC', tzinfo=None):
|
|
"""
|
|
Returns a list of datetime objects representing all available
|
|
datetimes for the given field_name, scoped to 'kind'.
|
|
"""
|
|
assert kind in ("year", "month", "day", "hour", "minute", "second"), \
|
|
"'kind' must be one of 'year', 'month', 'day', 'hour', 'minute' or 'second'."
|
|
assert order in ('ASC', 'DESC'), \
|
|
"'order' must be either 'ASC' or 'DESC'."
|
|
if settings.USE_TZ:
|
|
if tzinfo is None:
|
|
tzinfo = timezone.get_current_timezone()
|
|
else:
|
|
tzinfo = None
|
|
return self._clone(klass=DateTimeQuerySet, setup=True,
|
|
_field_name=field_name, _kind=kind, _order=order, _tzinfo=tzinfo)
|
|
|
|
def none(self):
|
|
"""
|
|
Returns an empty QuerySet.
|
|
"""
|
|
clone = self._clone()
|
|
clone.query.set_empty()
|
|
return clone
|
|
|
|
##################################################################
|
|
# PUBLIC METHODS THAT ALTER ATTRIBUTES AND RETURN A NEW QUERYSET #
|
|
##################################################################
|
|
|
|
def all(self):
|
|
"""
|
|
Returns a new QuerySet that is a copy of the current one. This allows a
|
|
QuerySet to proxy for a model manager in some cases.
|
|
"""
|
|
return self._clone()
|
|
|
|
def filter(self, *args, **kwargs):
|
|
"""
|
|
Returns a new QuerySet instance with the args ANDed to the existing
|
|
set.
|
|
"""
|
|
return self._filter_or_exclude(False, *args, **kwargs)
|
|
|
|
def exclude(self, *args, **kwargs):
|
|
"""
|
|
Returns a new QuerySet instance with NOT (args) ANDed to the existing
|
|
set.
|
|
"""
|
|
return self._filter_or_exclude(True, *args, **kwargs)
|
|
|
|
def _filter_or_exclude(self, negate, *args, **kwargs):
|
|
if args or kwargs:
|
|
assert self.query.can_filter(), \
|
|
"Cannot filter a query once a slice has been taken."
|
|
|
|
clone = self._clone()
|
|
if negate:
|
|
clone.query.add_q(~Q(*args, **kwargs))
|
|
else:
|
|
clone.query.add_q(Q(*args, **kwargs))
|
|
return clone
|
|
|
|
def complex_filter(self, filter_obj):
|
|
"""
|
|
Returns a new QuerySet instance with filter_obj added to the filters.
|
|
|
|
filter_obj can be a Q object (or anything with an add_to_query()
|
|
method) or a dictionary of keyword lookup arguments.
|
|
|
|
This exists to support framework features such as 'limit_choices_to',
|
|
and usually it will be more natural to use other methods.
|
|
"""
|
|
if isinstance(filter_obj, Q) or hasattr(filter_obj, 'add_to_query'):
|
|
clone = self._clone()
|
|
clone.query.add_q(filter_obj)
|
|
return clone
|
|
else:
|
|
return self._filter_or_exclude(None, **filter_obj)
|
|
|
|
def select_for_update(self, nowait=False):
|
|
"""
|
|
Returns a new QuerySet instance that will select objects with a
|
|
FOR UPDATE lock.
|
|
"""
|
|
obj = self._clone()
|
|
obj._for_write = True
|
|
obj.query.select_for_update = True
|
|
obj.query.select_for_update_nowait = nowait
|
|
return obj
|
|
|
|
def select_related(self, *fields):
|
|
"""
|
|
Returns a new QuerySet instance that will select related objects.
|
|
|
|
If fields are specified, they must be ForeignKey fields and only those
|
|
related objects are included in the selection.
|
|
|
|
If select_related(None) is called, the list is cleared.
|
|
"""
|
|
obj = self._clone()
|
|
if fields == (None,):
|
|
obj.query.select_related = False
|
|
elif fields:
|
|
obj.query.add_select_related(fields)
|
|
else:
|
|
obj.query.select_related = True
|
|
return obj
|
|
|
|
def prefetch_related(self, *lookups):
|
|
"""
|
|
Returns a new QuerySet instance that will prefetch the specified
|
|
Many-To-One and Many-To-Many related objects when the QuerySet is
|
|
evaluated.
|
|
|
|
When prefetch_related() is called more than once, the list of lookups to
|
|
prefetch is appended to. If prefetch_related(None) is called, the list
|
|
is cleared.
|
|
"""
|
|
clone = self._clone()
|
|
if lookups == (None,):
|
|
clone._prefetch_related_lookups = []
|
|
else:
|
|
clone._prefetch_related_lookups.extend(lookups)
|
|
return clone
|
|
|
|
def annotate(self, *args, **kwargs):
|
|
"""
|
|
Return a query set in which the returned objects have been annotated
|
|
with data aggregated from related fields.
|
|
"""
|
|
aggrs = OrderedDict() # To preserve ordering of args
|
|
for arg in args:
|
|
if arg.default_alias in kwargs:
|
|
raise ValueError("The named annotation '%s' conflicts with the "
|
|
"default name for another annotation."
|
|
% arg.default_alias)
|
|
aggrs[arg.default_alias] = arg
|
|
aggrs.update(kwargs)
|
|
|
|
names = getattr(self, '_fields', None)
|
|
if names is None:
|
|
names = set(self.model._meta.get_all_field_names())
|
|
for aggregate in aggrs:
|
|
if aggregate in names:
|
|
raise ValueError("The annotation '%s' conflicts with a field on "
|
|
"the model." % aggregate)
|
|
|
|
obj = self._clone()
|
|
|
|
obj._setup_aggregate_query(list(aggrs))
|
|
|
|
# Add the aggregates to the query
|
|
for (alias, aggregate_expr) in aggrs.items():
|
|
obj.query.add_aggregate(aggregate_expr, self.model, alias,
|
|
is_summary=False)
|
|
|
|
return obj
|
|
|
|
def order_by(self, *field_names):
|
|
"""
|
|
Returns a new QuerySet instance with the ordering changed.
|
|
"""
|
|
assert self.query.can_filter(), \
|
|
"Cannot reorder a query once a slice has been taken."
|
|
obj = self._clone()
|
|
obj.query.clear_ordering(force_empty=False)
|
|
obj.query.add_ordering(*field_names)
|
|
return obj
|
|
|
|
def distinct(self, *field_names):
|
|
"""
|
|
Returns a new QuerySet instance that will select only distinct results.
|
|
"""
|
|
assert self.query.can_filter(), \
|
|
"Cannot create distinct fields once a slice has been taken."
|
|
obj = self._clone()
|
|
obj.query.add_distinct_fields(*field_names)
|
|
return obj
|
|
|
|
def extra(self, select=None, where=None, params=None, tables=None,
|
|
order_by=None, select_params=None):
|
|
"""
|
|
Adds extra SQL fragments to the query.
|
|
"""
|
|
assert self.query.can_filter(), \
|
|
"Cannot change a query once a slice has been taken"
|
|
clone = self._clone()
|
|
clone.query.add_extra(select, select_params, where, params, tables, order_by)
|
|
return clone
|
|
|
|
def reverse(self):
|
|
"""
|
|
Reverses the ordering of the QuerySet.
|
|
"""
|
|
clone = self._clone()
|
|
clone.query.standard_ordering = not clone.query.standard_ordering
|
|
return clone
|
|
|
|
def defer(self, *fields):
|
|
"""
|
|
Defers the loading of data for certain fields until they are accessed.
|
|
The set of fields to defer is added to any existing set of deferred
|
|
fields. The only exception to this is if None is passed in as the only
|
|
parameter, in which case all deferrals are removed (None acts as a
|
|
reset option).
|
|
"""
|
|
clone = self._clone()
|
|
if fields == (None,):
|
|
clone.query.clear_deferred_loading()
|
|
else:
|
|
clone.query.add_deferred_loading(fields)
|
|
return clone
|
|
|
|
def only(self, *fields):
|
|
"""
|
|
Essentially, the opposite of defer. Only the fields passed into this
|
|
method and that are not already specified as deferred are loaded
|
|
immediately when the queryset is evaluated.
|
|
"""
|
|
if fields == (None,):
|
|
# Can only pass None to defer(), not only(), as the rest option.
|
|
# That won't stop people trying to do this, so let's be explicit.
|
|
raise TypeError("Cannot pass None as an argument to only().")
|
|
clone = self._clone()
|
|
clone.query.add_immediate_loading(fields)
|
|
return clone
|
|
|
|
def using(self, alias):
|
|
"""
|
|
Selects which database this QuerySet should execute its query against.
|
|
"""
|
|
clone = self._clone()
|
|
clone._db = alias
|
|
return clone
|
|
|
|
###################################
|
|
# PUBLIC INTROSPECTION ATTRIBUTES #
|
|
###################################
|
|
|
|
def ordered(self):
|
|
"""
|
|
Returns True if the QuerySet is ordered -- i.e. has an order_by()
|
|
clause or a default ordering on the model.
|
|
"""
|
|
if self.query.extra_order_by or self.query.order_by:
|
|
return True
|
|
elif self.query.default_ordering and self.query.get_meta().ordering:
|
|
return True
|
|
else:
|
|
return False
|
|
ordered = property(ordered)
|
|
|
|
@property
|
|
def db(self):
|
|
"Return the database that will be used if this query is executed now"
|
|
if self._for_write:
|
|
return self._db or router.db_for_write(self.model, **self._hints)
|
|
return self._db or router.db_for_read(self.model, **self._hints)
|
|
|
|
###################
|
|
# PRIVATE METHODS #
|
|
###################
|
|
|
|
def _insert(self, objs, fields, return_id=False, raw=False, using=None):
|
|
"""
|
|
Inserts a new record for the given model. This provides an interface to
|
|
the InsertQuery class and is how Model.save() is implemented.
|
|
"""
|
|
self._for_write = True
|
|
if using is None:
|
|
using = self.db
|
|
query = sql.InsertQuery(self.model)
|
|
query.insert_values(fields, objs, raw=raw)
|
|
return query.get_compiler(using=using).execute_sql(return_id)
|
|
_insert.alters_data = True
|
|
_insert.queryset_only = False
|
|
|
|
def _batched_insert(self, objs, fields, batch_size):
|
|
"""
|
|
A little helper method for bulk_insert to insert the bulk one batch
|
|
at a time. Inserts recursively a batch from the front of the bulk and
|
|
then _batched_insert() the remaining objects again.
|
|
"""
|
|
if not objs:
|
|
return
|
|
ops = connections[self.db].ops
|
|
batch_size = (batch_size or max(ops.bulk_batch_size(fields, objs), 1))
|
|
for batch in [objs[i:i + batch_size]
|
|
for i in range(0, len(objs), batch_size)]:
|
|
self.model._base_manager._insert(batch, fields=fields,
|
|
using=self.db)
|
|
|
|
def _clone(self, klass=None, setup=False, **kwargs):
|
|
if klass is None:
|
|
klass = self.__class__
|
|
elif not issubclass(self.__class__, klass):
|
|
base_queryset_class = getattr(self, '_base_queryset_class', self.__class__)
|
|
class_bases = (klass, base_queryset_class)
|
|
class_dict = {
|
|
'_base_queryset_class': base_queryset_class,
|
|
'_specialized_queryset_class': klass,
|
|
}
|
|
klass = type(klass.__name__, class_bases, class_dict)
|
|
|
|
query = self.query.clone()
|
|
if self._sticky_filter:
|
|
query.filter_is_sticky = True
|
|
c = klass(model=self.model, query=query, using=self._db, hints=self._hints)
|
|
c._for_write = self._for_write
|
|
c._prefetch_related_lookups = self._prefetch_related_lookups[:]
|
|
c._known_related_objects = self._known_related_objects
|
|
c.__dict__.update(kwargs)
|
|
if setup and hasattr(c, '_setup_query'):
|
|
c._setup_query()
|
|
return c
|
|
|
|
def _fetch_all(self):
|
|
if self._result_cache is None:
|
|
self._result_cache = list(self.iterator())
|
|
if self._prefetch_related_lookups and not self._prefetch_done:
|
|
self._prefetch_related_objects()
|
|
|
|
def _next_is_sticky(self):
|
|
"""
|
|
Indicates that the next filter call and the one following that should
|
|
be treated as a single filter. This is only important when it comes to
|
|
determining when to reuse tables for many-to-many filters. Required so
|
|
that we can filter naturally on the results of related managers.
|
|
|
|
This doesn't return a clone of the current QuerySet (it returns
|
|
"self"). The method is only used internally and should be immediately
|
|
followed by a filter() that does create a clone.
|
|
"""
|
|
self._sticky_filter = True
|
|
return self
|
|
|
|
def _merge_sanity_check(self, other):
|
|
"""
|
|
Checks that we are merging two comparable QuerySet classes. By default
|
|
this does nothing, but see the ValuesQuerySet for an example of where
|
|
it's useful.
|
|
"""
|
|
pass
|
|
|
|
def _merge_known_related_objects(self, other):
|
|
"""
|
|
Keep track of all known related objects from either QuerySet instance.
|
|
"""
|
|
for field, objects in other._known_related_objects.items():
|
|
self._known_related_objects.setdefault(field, {}).update(objects)
|
|
|
|
def _setup_aggregate_query(self, aggregates):
|
|
"""
|
|
Prepare the query for computing a result that contains aggregate annotations.
|
|
"""
|
|
opts = self.model._meta
|
|
if self.query.group_by is None:
|
|
field_names = [f.attname for f in opts.concrete_fields]
|
|
self.query.add_fields(field_names, False)
|
|
self.query.set_group_by()
|
|
|
|
def _prepare(self):
|
|
return self
|
|
|
|
def _as_sql(self, connection):
|
|
"""
|
|
Returns the internal query's SQL and parameters (as a tuple).
|
|
"""
|
|
obj = self.values("pk")
|
|
if obj._db is None or connection == connections[obj._db]:
|
|
return obj.query.get_compiler(connection=connection).as_nested_sql()
|
|
raise ValueError("Can't do subqueries with queries on different DBs.")
|
|
|
|
# When used as part of a nested query, a queryset will never be an "always
|
|
# empty" result.
|
|
value_annotation = True
|
|
|
|
def _add_hints(self, **hints):
|
|
"""
|
|
Update hinting information for later use by Routers
|
|
"""
|
|
# If there is any hinting information, add it to what we already know.
|
|
# If we have a new hint for an existing key, overwrite with the new value.
|
|
self._hints.update(hints)
|
|
|
|
def _has_filters(self):
|
|
"""
|
|
Checks if this QuerySet has any filtering going on. Note that this
|
|
isn't equivalent for checking if all objects are present in results,
|
|
for example qs[1:]._has_filters() -> False.
|
|
"""
|
|
return self.query.has_filters()
|
|
|
|
def is_compatible_query_object_type(self, opts):
|
|
model = self.model
|
|
return (
|
|
model == opts.concrete_model or
|
|
opts.concrete_model in model._meta.get_parent_list() or
|
|
model in opts.get_parent_list()
|
|
)
|
|
is_compatible_query_object_type.queryset_only = True
|
|
|
|
|
|
class InstanceCheckMeta(type):
|
|
def __instancecheck__(self, instance):
|
|
return instance.query.is_empty()
|
|
|
|
|
|
class EmptyQuerySet(six.with_metaclass(InstanceCheckMeta)):
|
|
"""
|
|
Marker class usable for checking if a queryset is empty by .none():
|
|
isinstance(qs.none(), EmptyQuerySet) -> True
|
|
"""
|
|
|
|
def __init__(self, *args, **kwargs):
|
|
raise TypeError("EmptyQuerySet can't be instantiated")
|
|
|
|
|
|
class ValuesQuerySet(QuerySet):
|
|
def __init__(self, *args, **kwargs):
|
|
super(ValuesQuerySet, self).__init__(*args, **kwargs)
|
|
# select_related isn't supported in values(). (FIXME -#3358)
|
|
self.query.select_related = False
|
|
|
|
# QuerySet.clone() will also set up the _fields attribute with the
|
|
# names of the model fields to select.
|
|
|
|
def only(self, *fields):
|
|
raise NotImplementedError("ValuesQuerySet does not implement only()")
|
|
|
|
def defer(self, *fields):
|
|
raise NotImplementedError("ValuesQuerySet does not implement defer()")
|
|
|
|
def iterator(self):
|
|
# Purge any extra columns that haven't been explicitly asked for
|
|
extra_names = list(self.query.extra_select)
|
|
field_names = self.field_names
|
|
aggregate_names = list(self.query.aggregate_select)
|
|
|
|
names = extra_names + field_names + aggregate_names
|
|
|
|
for row in self.query.get_compiler(self.db).results_iter():
|
|
yield dict(zip(names, row))
|
|
|
|
def delete(self):
|
|
# values().delete() doesn't work currently - make sure it raises an
|
|
# user friendly error.
|
|
raise TypeError("Queries with .values() or .values_list() applied "
|
|
"can't be deleted")
|
|
|
|
def _setup_query(self):
|
|
"""
|
|
Constructs the field_names list that the values query will be
|
|
retrieving.
|
|
|
|
Called by the _clone() method after initializing the rest of the
|
|
instance.
|
|
"""
|
|
self.query.clear_deferred_loading()
|
|
self.query.clear_select_fields()
|
|
|
|
if self._fields:
|
|
self.extra_names = []
|
|
self.aggregate_names = []
|
|
if not self.query._extra and not self.query._aggregates:
|
|
# Short cut - if there are no extra or aggregates, then
|
|
# the values() clause must be just field names.
|
|
self.field_names = list(self._fields)
|
|
else:
|
|
self.query.default_cols = False
|
|
self.field_names = []
|
|
for f in self._fields:
|
|
# we inspect the full extra_select list since we might
|
|
# be adding back an extra select item that we hadn't
|
|
# had selected previously.
|
|
if self.query._extra and f in self.query._extra:
|
|
self.extra_names.append(f)
|
|
elif f in self.query.aggregate_select:
|
|
self.aggregate_names.append(f)
|
|
else:
|
|
self.field_names.append(f)
|
|
else:
|
|
# Default to all fields.
|
|
self.extra_names = None
|
|
self.field_names = [f.attname for f in self.model._meta.concrete_fields]
|
|
self.aggregate_names = None
|
|
|
|
self.query.select = []
|
|
if self.extra_names is not None:
|
|
self.query.set_extra_mask(self.extra_names)
|
|
self.query.add_fields(self.field_names, True)
|
|
if self.aggregate_names is not None:
|
|
self.query.set_aggregate_mask(self.aggregate_names)
|
|
|
|
def _clone(self, klass=None, setup=False, **kwargs):
|
|
"""
|
|
Cloning a ValuesQuerySet preserves the current fields.
|
|
"""
|
|
c = super(ValuesQuerySet, self)._clone(klass, **kwargs)
|
|
if not hasattr(c, '_fields'):
|
|
# Only clone self._fields if _fields wasn't passed into the cloning
|
|
# call directly.
|
|
c._fields = self._fields[:]
|
|
c.field_names = self.field_names
|
|
c.extra_names = self.extra_names
|
|
c.aggregate_names = self.aggregate_names
|
|
if setup and hasattr(c, '_setup_query'):
|
|
c._setup_query()
|
|
return c
|
|
|
|
def _merge_sanity_check(self, other):
|
|
super(ValuesQuerySet, self)._merge_sanity_check(other)
|
|
if (set(self.extra_names) != set(other.extra_names) or
|
|
set(self.field_names) != set(other.field_names) or
|
|
self.aggregate_names != other.aggregate_names):
|
|
raise TypeError("Merging '%s' classes must involve the same values in each case."
|
|
% self.__class__.__name__)
|
|
|
|
def _setup_aggregate_query(self, aggregates):
|
|
"""
|
|
Prepare the query for computing a result that contains aggregate annotations.
|
|
"""
|
|
self.query.set_group_by()
|
|
|
|
if self.aggregate_names is not None:
|
|
self.aggregate_names.extend(aggregates)
|
|
self.query.set_aggregate_mask(self.aggregate_names)
|
|
|
|
super(ValuesQuerySet, self)._setup_aggregate_query(aggregates)
|
|
|
|
def _as_sql(self, connection):
|
|
"""
|
|
For ValuesQuerySet (and subclasses like ValuesListQuerySet), they can
|
|
only be used as nested queries if they're already set up to select only
|
|
a single field (in which case, that is the field column that is
|
|
returned). This differs from QuerySet.as_sql(), where the column to
|
|
select is set up by Django.
|
|
"""
|
|
if ((self._fields and len(self._fields) > 1) or
|
|
(not self._fields and len(self.model._meta.fields) > 1)):
|
|
raise TypeError('Cannot use a multi-field %s as a filter value.'
|
|
% self.__class__.__name__)
|
|
|
|
obj = self._clone()
|
|
if obj._db is None or connection == connections[obj._db]:
|
|
return obj.query.get_compiler(connection=connection).as_nested_sql()
|
|
raise ValueError("Can't do subqueries with queries on different DBs.")
|
|
|
|
def _prepare(self):
|
|
"""
|
|
Validates that we aren't trying to do a query like
|
|
value__in=qs.values('value1', 'value2'), which isn't valid.
|
|
"""
|
|
if ((self._fields and len(self._fields) > 1) or
|
|
(not self._fields and len(self.model._meta.fields) > 1)):
|
|
raise TypeError('Cannot use a multi-field %s as a filter value.'
|
|
% self.__class__.__name__)
|
|
return self
|
|
|
|
def is_compatible_query_object_type(self, opts):
|
|
"""
|
|
ValueQuerySets do not need to be checked for compatibility.
|
|
We trust that users of ValueQuerySets know what they are doing.
|
|
"""
|
|
return True
|
|
|
|
|
|
class ValuesListQuerySet(ValuesQuerySet):
|
|
def iterator(self):
|
|
if self.flat and len(self._fields) == 1:
|
|
for row in self.query.get_compiler(self.db).results_iter():
|
|
yield row[0]
|
|
elif not self.query.extra_select and not self.query.aggregate_select:
|
|
for row in self.query.get_compiler(self.db).results_iter():
|
|
yield tuple(row)
|
|
else:
|
|
# When extra(select=...) or an annotation is involved, the extra
|
|
# cols are always at the start of the row, and we need to reorder
|
|
# the fields to match the order in self._fields.
|
|
extra_names = list(self.query.extra_select)
|
|
field_names = self.field_names
|
|
aggregate_names = list(self.query.aggregate_select)
|
|
|
|
names = extra_names + field_names + aggregate_names
|
|
|
|
# If a field list has been specified, use it. Otherwise, use the
|
|
# full list of fields, including extras and aggregates.
|
|
if self._fields:
|
|
fields = list(self._fields) + [f for f in aggregate_names if f not in self._fields]
|
|
else:
|
|
fields = names
|
|
|
|
for row in self.query.get_compiler(self.db).results_iter():
|
|
data = dict(zip(names, row))
|
|
yield tuple(data[f] for f in fields)
|
|
|
|
def _clone(self, *args, **kwargs):
|
|
clone = super(ValuesListQuerySet, self)._clone(*args, **kwargs)
|
|
if not hasattr(clone, "flat"):
|
|
# Only assign flat if the clone didn't already get it from kwargs
|
|
clone.flat = self.flat
|
|
return clone
|
|
|
|
|
|
class DateQuerySet(QuerySet):
|
|
def iterator(self):
|
|
return self.query.get_compiler(self.db).results_iter()
|
|
|
|
def _setup_query(self):
|
|
"""
|
|
Sets up any special features of the query attribute.
|
|
|
|
Called by the _clone() method after initializing the rest of the
|
|
instance.
|
|
"""
|
|
self.query.clear_deferred_loading()
|
|
self.query = self.query.clone(klass=sql.DateQuery, setup=True)
|
|
self.query.select = []
|
|
self.query.add_select(self._field_name, self._kind, self._order)
|
|
|
|
def _clone(self, klass=None, setup=False, **kwargs):
|
|
c = super(DateQuerySet, self)._clone(klass, False, **kwargs)
|
|
c._field_name = self._field_name
|
|
c._kind = self._kind
|
|
if setup and hasattr(c, '_setup_query'):
|
|
c._setup_query()
|
|
return c
|
|
|
|
|
|
class DateTimeQuerySet(QuerySet):
|
|
def iterator(self):
|
|
return self.query.get_compiler(self.db).results_iter()
|
|
|
|
def _setup_query(self):
|
|
"""
|
|
Sets up any special features of the query attribute.
|
|
|
|
Called by the _clone() method after initializing the rest of the
|
|
instance.
|
|
"""
|
|
self.query.clear_deferred_loading()
|
|
self.query = self.query.clone(klass=sql.DateTimeQuery, setup=True, tzinfo=self._tzinfo)
|
|
self.query.select = []
|
|
self.query.add_select(self._field_name, self._kind, self._order)
|
|
|
|
def _clone(self, klass=None, setup=False, **kwargs):
|
|
c = super(DateTimeQuerySet, self)._clone(klass, False, **kwargs)
|
|
c._field_name = self._field_name
|
|
c._kind = self._kind
|
|
c._tzinfo = self._tzinfo
|
|
if setup and hasattr(c, '_setup_query'):
|
|
c._setup_query()
|
|
return c
|
|
|
|
|
|
def get_klass_info(klass, max_depth=0, cur_depth=0, requested=None,
|
|
only_load=None, from_parent=None):
|
|
"""
|
|
Helper function that recursively returns an information for a klass, to be
|
|
used in get_cached_row. It exists just to compute this information only
|
|
once for entire queryset. Otherwise it would be computed for each row, which
|
|
leads to poor performance on large querysets.
|
|
|
|
Arguments:
|
|
* klass - the class to retrieve (and instantiate)
|
|
* max_depth - the maximum depth to which a select_related()
|
|
relationship should be explored.
|
|
* cur_depth - the current depth in the select_related() tree.
|
|
Used in recursive calls to determine if we should dig deeper.
|
|
* requested - A dictionary describing the select_related() tree
|
|
that is to be retrieved. keys are field names; values are
|
|
dictionaries describing the keys on that related object that
|
|
are themselves to be select_related().
|
|
* only_load - if the query has had only() or defer() applied,
|
|
this is the list of field names that will be returned. If None,
|
|
the full field list for `klass` can be assumed.
|
|
* from_parent - the parent model used to get to this model
|
|
|
|
Note that when travelling from parent to child, we will only load child
|
|
fields which aren't in the parent.
|
|
"""
|
|
if max_depth and requested is None and cur_depth > max_depth:
|
|
# We've recursed deeply enough; stop now.
|
|
return None
|
|
|
|
if only_load:
|
|
load_fields = only_load.get(klass) or set()
|
|
# When we create the object, we will also be creating populating
|
|
# all the parent classes, so traverse the parent classes looking
|
|
# for fields that must be included on load.
|
|
for parent in klass._meta.get_parent_list():
|
|
fields = only_load.get(parent)
|
|
if fields:
|
|
load_fields.update(fields)
|
|
else:
|
|
load_fields = None
|
|
|
|
if load_fields:
|
|
# Handle deferred fields.
|
|
skip = set()
|
|
init_list = []
|
|
# Build the list of fields that *haven't* been requested
|
|
for field, model in klass._meta.get_concrete_fields_with_model():
|
|
if from_parent and model and issubclass(from_parent, model):
|
|
# Avoid loading fields already loaded for parent model for
|
|
# child models.
|
|
continue
|
|
elif field.name not in load_fields:
|
|
skip.add(field.attname)
|
|
else:
|
|
init_list.append(field.attname)
|
|
# Retrieve all the requested fields
|
|
field_count = len(init_list)
|
|
if skip:
|
|
klass = deferred_class_factory(klass, skip)
|
|
field_names = init_list
|
|
else:
|
|
field_names = ()
|
|
else:
|
|
# Load all fields on klass
|
|
|
|
field_count = len(klass._meta.concrete_fields)
|
|
# Check if we need to skip some parent fields.
|
|
if from_parent and len(klass._meta.local_concrete_fields) != len(klass._meta.concrete_fields):
|
|
# Only load those fields which haven't been already loaded into
|
|
# 'from_parent'.
|
|
non_seen_models = [p for p in klass._meta.get_parent_list()
|
|
if not issubclass(from_parent, p)]
|
|
# Load local fields, too...
|
|
non_seen_models.append(klass)
|
|
field_names = [f.attname for f in klass._meta.concrete_fields
|
|
if f.model in non_seen_models]
|
|
field_count = len(field_names)
|
|
# Try to avoid populating field_names variable for performance reasons.
|
|
# If field_names variable is set, we use **kwargs based model init
|
|
# which is slower than normal init.
|
|
if field_count == len(klass._meta.concrete_fields):
|
|
field_names = ()
|
|
|
|
restricted = requested is not None
|
|
|
|
related_fields = []
|
|
for f in klass._meta.fields:
|
|
if select_related_descend(f, restricted, requested, load_fields):
|
|
if restricted:
|
|
next = requested[f.name]
|
|
else:
|
|
next = None
|
|
klass_info = get_klass_info(f.rel.to, max_depth=max_depth, cur_depth=cur_depth + 1,
|
|
requested=next, only_load=only_load)
|
|
related_fields.append((f, klass_info))
|
|
|
|
reverse_related_fields = []
|
|
if restricted:
|
|
for o in klass._meta.get_all_related_objects():
|
|
if o.field.unique and select_related_descend(o.field, restricted, requested,
|
|
only_load.get(o.model), reverse=True):
|
|
next = requested[o.field.related_query_name()]
|
|
parent = klass if issubclass(o.model, klass) else None
|
|
klass_info = get_klass_info(o.model, max_depth=max_depth, cur_depth=cur_depth + 1,
|
|
requested=next, only_load=only_load, from_parent=parent)
|
|
reverse_related_fields.append((o.field, klass_info))
|
|
if field_names:
|
|
pk_idx = field_names.index(klass._meta.pk.attname)
|
|
else:
|
|
pk_idx = klass._meta.pk_index()
|
|
|
|
return klass, field_names, field_count, related_fields, reverse_related_fields, pk_idx
|
|
|
|
|
|
def reorder_for_init(model, field_names, values):
|
|
"""
|
|
Reorders given field names and values for those fields
|
|
to be in the same order as model.__init__() expects to find them.
|
|
"""
|
|
new_names, new_values = [], []
|
|
for f in model._meta.concrete_fields:
|
|
if f.attname not in field_names:
|
|
continue
|
|
new_names.append(f.attname)
|
|
new_values.append(values[field_names.index(f.attname)])
|
|
assert len(new_names) == len(field_names)
|
|
return new_names, new_values
|
|
|
|
|
|
def get_cached_row(row, index_start, using, klass_info, offset=0,
|
|
parent_data=()):
|
|
"""
|
|
Helper function that recursively returns an object with the specified
|
|
related attributes already populated.
|
|
|
|
This method may be called recursively to populate deep select_related()
|
|
clauses.
|
|
|
|
Arguments:
|
|
* row - the row of data returned by the database cursor
|
|
* index_start - the index of the row at which data for this
|
|
object is known to start
|
|
* offset - the number of additional fields that are known to
|
|
exist in row for `klass`. This usually means the number of
|
|
annotated results on `klass`.
|
|
* using - the database alias on which the query is being executed.
|
|
* klass_info - result of the get_klass_info function
|
|
* parent_data - parent model data in format (field, value). Used
|
|
to populate the non-local fields of child models.
|
|
"""
|
|
if klass_info is None:
|
|
return None
|
|
klass, field_names, field_count, related_fields, reverse_related_fields, pk_idx = klass_info
|
|
|
|
fields = row[index_start:index_start + field_count]
|
|
# If the pk column is None (or the equivalent '' in the case the
|
|
# connection interprets empty strings as nulls), then the related
|
|
# object must be non-existent - set the relation to None.
|
|
if (fields[pk_idx] is None or
|
|
(connections[using].features.interprets_empty_strings_as_nulls and
|
|
fields[pk_idx] == '')):
|
|
obj = None
|
|
elif field_names:
|
|
values = list(fields)
|
|
parent_values = []
|
|
parent_field_names = []
|
|
for rel_field, value in parent_data:
|
|
parent_field_names.append(rel_field.attname)
|
|
parent_values.append(value)
|
|
field_names, values = reorder_for_init(
|
|
klass, parent_field_names + field_names,
|
|
parent_values + values)
|
|
obj = klass.from_db(using, field_names, values)
|
|
else:
|
|
field_names = [f.attname for f in klass._meta.concrete_fields]
|
|
obj = klass.from_db(using, field_names, fields)
|
|
# Instantiate related fields
|
|
index_end = index_start + field_count + offset
|
|
# Iterate over each related object, populating any
|
|
# select_related() fields
|
|
for f, klass_info in related_fields:
|
|
# Recursively retrieve the data for the related object
|
|
cached_row = get_cached_row(row, index_end, using, klass_info)
|
|
# If the recursive descent found an object, populate the
|
|
# descriptor caches relevant to the object
|
|
if cached_row:
|
|
rel_obj, index_end = cached_row
|
|
if obj is not None:
|
|
# If the base object exists, populate the
|
|
# descriptor cache
|
|
setattr(obj, f.get_cache_name(), rel_obj)
|
|
if f.unique and rel_obj is not None:
|
|
# If the field is unique, populate the
|
|
# reverse descriptor cache on the related object
|
|
setattr(rel_obj, f.related.get_cache_name(), obj)
|
|
|
|
# Now do the same, but for reverse related objects.
|
|
# Only handle the restricted case - i.e., don't do a depth
|
|
# descent into reverse relations unless explicitly requested
|
|
for f, klass_info in reverse_related_fields:
|
|
# Transfer data from this object to childs.
|
|
parent_data = []
|
|
for rel_field, rel_model in klass_info[0]._meta.get_fields_with_model():
|
|
if rel_model is not None and isinstance(obj, rel_model):
|
|
parent_data.append((rel_field, getattr(obj, rel_field.attname)))
|
|
# Recursively retrieve the data for the related object
|
|
cached_row = get_cached_row(row, index_end, using, klass_info,
|
|
parent_data=parent_data)
|
|
# If the recursive descent found an object, populate the
|
|
# descriptor caches relevant to the object
|
|
if cached_row:
|
|
rel_obj, index_end = cached_row
|
|
if obj is not None:
|
|
# populate the reverse descriptor cache
|
|
setattr(obj, f.related.get_cache_name(), rel_obj)
|
|
if rel_obj is not None:
|
|
# If the related object exists, populate
|
|
# the descriptor cache.
|
|
setattr(rel_obj, f.get_cache_name(), obj)
|
|
# Populate related object caches using parent data.
|
|
for rel_field, _ in parent_data:
|
|
if rel_field.rel:
|
|
setattr(rel_obj, rel_field.attname, getattr(obj, rel_field.attname))
|
|
try:
|
|
cached_obj = getattr(obj, rel_field.get_cache_name())
|
|
setattr(rel_obj, rel_field.get_cache_name(), cached_obj)
|
|
except AttributeError:
|
|
# Related object hasn't been cached yet
|
|
pass
|
|
return obj, index_end
|
|
|
|
|
|
class RawQuerySet(object):
|
|
"""
|
|
Provides an iterator which converts the results of raw SQL queries into
|
|
annotated model instances.
|
|
"""
|
|
def __init__(self, raw_query, model=None, query=None, params=None,
|
|
translations=None, using=None, hints=None):
|
|
self.raw_query = raw_query
|
|
self.model = model
|
|
self._db = using
|
|
self._hints = hints or {}
|
|
self.query = query or sql.RawQuery(sql=raw_query, using=self.db, params=params)
|
|
self.params = params or ()
|
|
self.translations = translations or {}
|
|
|
|
def resolve_model_init_order(self):
|
|
"""
|
|
Resolve the init field names and value positions
|
|
"""
|
|
model_init_names = [f.attname for f in self.model._meta.fields
|
|
if f.attname in self.columns]
|
|
annotation_fields = [(column, pos) for pos, column in enumerate(self.columns)
|
|
if column not in self.model_fields]
|
|
model_init_order = [self.columns.index(fname) for fname in model_init_names]
|
|
return model_init_names, model_init_order, annotation_fields
|
|
|
|
def __iter__(self):
|
|
# Cache some things for performance reasons outside the loop.
|
|
db = self.db
|
|
compiler = connections[db].ops.compiler('SQLCompiler')(
|
|
self.query, connections[db], db
|
|
)
|
|
|
|
query = iter(self.query)
|
|
|
|
try:
|
|
model_init_names, model_init_pos, annotation_fields = self.resolve_model_init_order()
|
|
|
|
# Find out which model's fields are not present in the query.
|
|
skip = set()
|
|
for field in self.model._meta.fields:
|
|
if field.attname not in model_init_names:
|
|
skip.add(field.attname)
|
|
if skip:
|
|
if self.model._meta.pk.attname in skip:
|
|
raise InvalidQuery('Raw query must include the primary key')
|
|
model_cls = deferred_class_factory(self.model, skip)
|
|
else:
|
|
model_cls = self.model
|
|
fields = [self.model_fields.get(c, None) for c in self.columns]
|
|
converters = compiler.get_converters(fields)
|
|
for values in query:
|
|
if converters:
|
|
values = compiler.apply_converters(values, converters)
|
|
# Associate fields to values
|
|
model_init_values = [values[pos] for pos in model_init_pos]
|
|
instance = model_cls.from_db(db, model_init_names, model_init_values)
|
|
if annotation_fields:
|
|
for column, pos in annotation_fields:
|
|
setattr(instance, column, values[pos])
|
|
yield instance
|
|
finally:
|
|
# Done iterating the Query. If it has its own cursor, close it.
|
|
if hasattr(self.query, 'cursor') and self.query.cursor:
|
|
self.query.cursor.close()
|
|
|
|
def __repr__(self):
|
|
return "<RawQuerySet: %s>" % self.query
|
|
|
|
def __getitem__(self, k):
|
|
return list(self)[k]
|
|
|
|
@property
|
|
def db(self):
|
|
"Return the database that will be used if this query is executed now"
|
|
return self._db or router.db_for_read(self.model, **self._hints)
|
|
|
|
def using(self, alias):
|
|
"""
|
|
Selects which database this Raw QuerySet should execute its query against.
|
|
"""
|
|
return RawQuerySet(self.raw_query, model=self.model,
|
|
query=self.query.clone(using=alias),
|
|
params=self.params, translations=self.translations,
|
|
using=alias)
|
|
|
|
@property
|
|
def columns(self):
|
|
"""
|
|
A list of model field names in the order they'll appear in the
|
|
query results.
|
|
"""
|
|
if not hasattr(self, '_columns'):
|
|
self._columns = self.query.get_columns()
|
|
|
|
# Adjust any column names which don't match field names
|
|
for (query_name, model_name) in self.translations.items():
|
|
try:
|
|
index = self._columns.index(query_name)
|
|
self._columns[index] = model_name
|
|
except ValueError:
|
|
# Ignore translations for non-existent column names
|
|
pass
|
|
|
|
return self._columns
|
|
|
|
@property
|
|
def model_fields(self):
|
|
"""
|
|
A dict mapping column names to model field names.
|
|
"""
|
|
if not hasattr(self, '_model_fields'):
|
|
converter = connections[self.db].introspection.table_name_converter
|
|
self._model_fields = {}
|
|
for field in self.model._meta.fields:
|
|
name, column = field.get_attname_column()
|
|
self._model_fields[converter(column)] = field
|
|
return self._model_fields
|
|
|
|
|
|
class Prefetch(object):
|
|
def __init__(self, lookup, queryset=None, to_attr=None):
|
|
# `prefetch_through` is the path we traverse to perform the prefetch.
|
|
self.prefetch_through = lookup
|
|
# `prefetch_to` is the path to the attribute that stores the result.
|
|
self.prefetch_to = lookup
|
|
if to_attr:
|
|
self.prefetch_to = LOOKUP_SEP.join(lookup.split(LOOKUP_SEP)[:-1] + [to_attr])
|
|
|
|
self.queryset = queryset
|
|
self.to_attr = to_attr
|
|
|
|
def add_prefix(self, prefix):
|
|
self.prefetch_through = LOOKUP_SEP.join([prefix, self.prefetch_through])
|
|
self.prefetch_to = LOOKUP_SEP.join([prefix, self.prefetch_to])
|
|
|
|
def get_current_prefetch_through(self, level):
|
|
return LOOKUP_SEP.join(self.prefetch_through.split(LOOKUP_SEP)[:level + 1])
|
|
|
|
def get_current_prefetch_to(self, level):
|
|
return LOOKUP_SEP.join(self.prefetch_to.split(LOOKUP_SEP)[:level + 1])
|
|
|
|
def get_current_to_attr(self, level):
|
|
parts = self.prefetch_to.split(LOOKUP_SEP)
|
|
to_attr = parts[level]
|
|
as_attr = self.to_attr and level == len(parts) - 1
|
|
return to_attr, as_attr
|
|
|
|
def get_current_queryset(self, level):
|
|
if self.get_current_prefetch_to(level) == self.prefetch_to:
|
|
return self.queryset
|
|
return None
|
|
|
|
def __eq__(self, other):
|
|
if isinstance(other, Prefetch):
|
|
return self.prefetch_to == other.prefetch_to
|
|
return False
|
|
|
|
def __hash__(self):
|
|
return hash(self.__class__) ^ hash(self.prefetch_to)
|
|
|
|
|
|
def normalize_prefetch_lookups(lookups, prefix=None):
|
|
"""
|
|
Helper function that normalize lookups into Prefetch objects.
|
|
"""
|
|
ret = []
|
|
for lookup in lookups:
|
|
if not isinstance(lookup, Prefetch):
|
|
lookup = Prefetch(lookup)
|
|
if prefix:
|
|
lookup.add_prefix(prefix)
|
|
ret.append(lookup)
|
|
return ret
|
|
|
|
|
|
def prefetch_related_objects(result_cache, related_lookups):
|
|
"""
|
|
Helper function for prefetch_related functionality
|
|
|
|
Populates prefetched objects caches for a list of results
|
|
from a QuerySet
|
|
"""
|
|
|
|
if len(result_cache) == 0:
|
|
return # nothing to do
|
|
|
|
related_lookups = normalize_prefetch_lookups(related_lookups)
|
|
|
|
# We need to be able to dynamically add to the list of prefetch_related
|
|
# lookups that we look up (see below). So we need some book keeping to
|
|
# ensure we don't do duplicate work.
|
|
done_queries = {} # dictionary of things like 'foo__bar': [results]
|
|
|
|
auto_lookups = set() # we add to this as we go through.
|
|
followed_descriptors = set() # recursion protection
|
|
|
|
all_lookups = deque(related_lookups)
|
|
while all_lookups:
|
|
lookup = all_lookups.popleft()
|
|
if lookup.prefetch_to in done_queries:
|
|
if lookup.queryset:
|
|
raise ValueError("'%s' lookup was already seen with a different queryset. "
|
|
"You may need to adjust the ordering of your lookups." % lookup.prefetch_to)
|
|
|
|
continue
|
|
|
|
# Top level, the list of objects to decorate is the result cache
|
|
# from the primary QuerySet. It won't be for deeper levels.
|
|
obj_list = result_cache
|
|
|
|
through_attrs = lookup.prefetch_through.split(LOOKUP_SEP)
|
|
for level, through_attr in enumerate(through_attrs):
|
|
# Prepare main instances
|
|
if len(obj_list) == 0:
|
|
break
|
|
|
|
prefetch_to = lookup.get_current_prefetch_to(level)
|
|
if prefetch_to in done_queries:
|
|
# Skip any prefetching, and any object preparation
|
|
obj_list = done_queries[prefetch_to]
|
|
continue
|
|
|
|
# Prepare objects:
|
|
good_objects = True
|
|
for obj in obj_list:
|
|
# Since prefetching can re-use instances, it is possible to have
|
|
# the same instance multiple times in obj_list, so obj might
|
|
# already be prepared.
|
|
if not hasattr(obj, '_prefetched_objects_cache'):
|
|
try:
|
|
obj._prefetched_objects_cache = {}
|
|
except AttributeError:
|
|
# Must be in a QuerySet subclass that is not returning
|
|
# Model instances, either in Django or 3rd
|
|
# party. prefetch_related() doesn't make sense, so quit
|
|
# now.
|
|
good_objects = False
|
|
break
|
|
if not good_objects:
|
|
break
|
|
|
|
# Descend down tree
|
|
|
|
# We assume that objects retrieved are homogeneous (which is the premise
|
|
# of prefetch_related), so what applies to first object applies to all.
|
|
first_obj = obj_list[0]
|
|
prefetcher, descriptor, attr_found, is_fetched = get_prefetcher(first_obj, through_attr)
|
|
|
|
if not attr_found:
|
|
raise AttributeError("Cannot find '%s' on %s object, '%s' is an invalid "
|
|
"parameter to prefetch_related()" %
|
|
(through_attr, first_obj.__class__.__name__, lookup.prefetch_through))
|
|
|
|
if level == len(through_attrs) - 1 and prefetcher is None:
|
|
# Last one, this *must* resolve to something that supports
|
|
# prefetching, otherwise there is no point adding it and the
|
|
# developer asking for it has made a mistake.
|
|
raise ValueError("'%s' does not resolve to an item that supports "
|
|
"prefetching - this is an invalid parameter to "
|
|
"prefetch_related()." % lookup.prefetch_through)
|
|
|
|
if prefetcher is not None and not is_fetched:
|
|
obj_list, additional_lookups = prefetch_one_level(obj_list, prefetcher, lookup, level)
|
|
# We need to ensure we don't keep adding lookups from the
|
|
# same relationships to stop infinite recursion. So, if we
|
|
# are already on an automatically added lookup, don't add
|
|
# the new lookups from relationships we've seen already.
|
|
if not (lookup in auto_lookups and descriptor in followed_descriptors):
|
|
done_queries[prefetch_to] = obj_list
|
|
new_lookups = normalize_prefetch_lookups(additional_lookups, prefetch_to)
|
|
auto_lookups.update(new_lookups)
|
|
all_lookups.extendleft(new_lookups)
|
|
followed_descriptors.add(descriptor)
|
|
else:
|
|
# Either a singly related object that has already been fetched
|
|
# (e.g. via select_related), or hopefully some other property
|
|
# that doesn't support prefetching but needs to be traversed.
|
|
|
|
# We replace the current list of parent objects with the list
|
|
# of related objects, filtering out empty or missing values so
|
|
# that we can continue with nullable or reverse relations.
|
|
new_obj_list = []
|
|
for obj in obj_list:
|
|
try:
|
|
new_obj = getattr(obj, through_attr)
|
|
except exceptions.ObjectDoesNotExist:
|
|
continue
|
|
if new_obj is None:
|
|
continue
|
|
# We special-case `list` rather than something more generic
|
|
# like `Iterable` because we don't want to accidentally match
|
|
# user models that define __iter__.
|
|
if isinstance(new_obj, list):
|
|
new_obj_list.extend(new_obj)
|
|
else:
|
|
new_obj_list.append(new_obj)
|
|
obj_list = new_obj_list
|
|
|
|
|
|
def get_prefetcher(instance, attr):
|
|
"""
|
|
For the attribute 'attr' on the given instance, finds
|
|
an object that has a get_prefetch_queryset().
|
|
Returns a 4 tuple containing:
|
|
(the object with get_prefetch_queryset (or None),
|
|
the descriptor object representing this relationship (or None),
|
|
a boolean that is False if the attribute was not found at all,
|
|
a boolean that is True if the attribute has already been fetched)
|
|
"""
|
|
prefetcher = None
|
|
is_fetched = False
|
|
|
|
# For singly related objects, we have to avoid getting the attribute
|
|
# from the object, as this will trigger the query. So we first try
|
|
# on the class, in order to get the descriptor object.
|
|
rel_obj_descriptor = getattr(instance.__class__, attr, None)
|
|
if rel_obj_descriptor is None:
|
|
attr_found = hasattr(instance, attr)
|
|
else:
|
|
attr_found = True
|
|
if rel_obj_descriptor:
|
|
# singly related object, descriptor object has the
|
|
# get_prefetch_queryset() method.
|
|
if hasattr(rel_obj_descriptor, 'get_prefetch_queryset'):
|
|
prefetcher = rel_obj_descriptor
|
|
if rel_obj_descriptor.is_cached(instance):
|
|
is_fetched = True
|
|
else:
|
|
# descriptor doesn't support prefetching, so we go ahead and get
|
|
# the attribute on the instance rather than the class to
|
|
# support many related managers
|
|
rel_obj = getattr(instance, attr)
|
|
if hasattr(rel_obj, 'get_prefetch_queryset'):
|
|
prefetcher = rel_obj
|
|
return prefetcher, rel_obj_descriptor, attr_found, is_fetched
|
|
|
|
|
|
def prefetch_one_level(instances, prefetcher, lookup, level):
|
|
"""
|
|
Helper function for prefetch_related_objects
|
|
|
|
Runs prefetches on all instances using the prefetcher object,
|
|
assigning results to relevant caches in instance.
|
|
|
|
The prefetched objects are returned, along with any additional
|
|
prefetches that must be done due to prefetch_related lookups
|
|
found from default managers.
|
|
"""
|
|
# prefetcher must have a method get_prefetch_queryset() which takes a list
|
|
# of instances, and returns a tuple:
|
|
|
|
# (queryset of instances of self.model that are related to passed in instances,
|
|
# callable that gets value to be matched for returned instances,
|
|
# callable that gets value to be matched for passed in instances,
|
|
# boolean that is True for singly related objects,
|
|
# cache name to assign to).
|
|
|
|
# The 'values to be matched' must be hashable as they will be used
|
|
# in a dictionary.
|
|
|
|
rel_qs, rel_obj_attr, instance_attr, single, cache_name = (
|
|
prefetcher.get_prefetch_queryset(instances, lookup.get_current_queryset(level)))
|
|
# We have to handle the possibility that the QuerySet we just got back
|
|
# contains some prefetch_related lookups. We don't want to trigger the
|
|
# prefetch_related functionality by evaluating the query. Rather, we need
|
|
# to merge in the prefetch_related lookups.
|
|
additional_lookups = getattr(rel_qs, '_prefetch_related_lookups', [])
|
|
if additional_lookups:
|
|
# Don't need to clone because the manager should have given us a fresh
|
|
# instance, so we access an internal instead of using public interface
|
|
# for performance reasons.
|
|
rel_qs._prefetch_related_lookups = []
|
|
|
|
all_related_objects = list(rel_qs)
|
|
|
|
rel_obj_cache = {}
|
|
for rel_obj in all_related_objects:
|
|
rel_attr_val = rel_obj_attr(rel_obj)
|
|
rel_obj_cache.setdefault(rel_attr_val, []).append(rel_obj)
|
|
|
|
for obj in instances:
|
|
instance_attr_val = instance_attr(obj)
|
|
vals = rel_obj_cache.get(instance_attr_val, [])
|
|
to_attr, as_attr = lookup.get_current_to_attr(level)
|
|
if single:
|
|
val = vals[0] if vals else None
|
|
to_attr = to_attr if as_attr else cache_name
|
|
setattr(obj, to_attr, val)
|
|
else:
|
|
if as_attr:
|
|
setattr(obj, to_attr, vals)
|
|
else:
|
|
# Cache in the QuerySet.all().
|
|
qs = getattr(obj, to_attr).all()
|
|
qs._result_cache = vals
|
|
# We don't want the individual qs doing prefetch_related now,
|
|
# since we have merged this into the current work.
|
|
qs._prefetch_done = True
|
|
obj._prefetched_objects_cache[cache_name] = qs
|
|
return all_related_objects, additional_lookups
|