1537 lines
61 KiB
Python
1537 lines
61 KiB
Python
"""
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Create SQL statements for QuerySets.
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The code in here encapsulates all of the SQL construction so that QuerySets
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themselves do not have to (and could be backed by things other than SQL
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databases). The abstraction barrier only works one way: this module has to know
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all about the internals of models in order to get the information it needs.
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"""
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from copy import deepcopy
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from django.utils.tree import Node
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from django.utils.datastructures import SortedDict
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from django.dispatch import dispatcher
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from django.db import connection
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from django.db.models import signals
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from django.db.models.sql.where import WhereNode, EverythingNode, AND, OR
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from django.db.models.sql.datastructures import Count
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from django.db.models.fields import FieldDoesNotExist
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from django.core.exceptions import FieldError
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from datastructures import EmptyResultSet, Empty, MultiJoin
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from constants import *
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try:
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set
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except NameError:
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from sets import Set as set # Python 2.3 fallback
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__all__ = ['Query']
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class Query(object):
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"""
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A single SQL query.
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"""
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# SQL join types. These are part of the class because their string forms
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# vary from database to database and can be customised by a subclass.
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INNER = 'INNER JOIN'
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LOUTER = 'LEFT OUTER JOIN'
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alias_prefix = 'T'
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query_terms = QUERY_TERMS
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def __init__(self, model, connection, where=WhereNode):
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self.model = model
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self.connection = connection
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self.alias_refcount = {}
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self.alias_map = {} # Maps alias to join information
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self.table_map = {} # Maps table names to list of aliases.
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self.join_map = {}
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self.rev_join_map = {} # Reverse of join_map.
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self.quote_cache = {}
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self.default_cols = True
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self.default_ordering = True
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self.standard_ordering = True
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self.ordering_aliases = []
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self.start_meta = None
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self.select_fields = []
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self.related_select_fields = []
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# SQL-related attributes
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self.select = []
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self.tables = [] # Aliases in the order they are created.
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self.where = where()
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self.where_class = where
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self.group_by = []
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self.having = []
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self.order_by = []
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self.low_mark, self.high_mark = 0, None # Used for offset/limit
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self.distinct = False
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self.select_related = False
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self.related_select_cols = []
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# Arbitrary maximum limit for select_related. Prevents infinite
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# recursion. Can be changed by the depth parameter to select_related().
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self.max_depth = 5
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# These are for extensions. The contents are more or less appended
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# verbatim to the appropriate clause.
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self.extra_select = {} # Maps col_alias -> col_sql.
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self.extra_select_params = ()
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self.extra_tables = ()
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self.extra_where = ()
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self.extra_params = ()
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self.extra_order_by = ()
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def __str__(self):
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"""
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Returns the query as a string of SQL with the parameter values
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substituted in.
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Parameter values won't necessarily be quoted correctly, since that is
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done by the database interface at execution time.
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"""
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sql, params = self.as_sql()
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return sql % params
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def __deepcopy__(self, memo):
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result= self.clone()
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memo[id(self)] = result
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return result
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def __getstate__(self):
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"""
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Pickling support.
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"""
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obj_dict = self.__dict__.copy()
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del obj_dict['connection']
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return obj_dict
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def __setstate__(self, obj_dict):
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"""
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Unpickling support.
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"""
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self.__dict__.update(obj_dict)
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# XXX: Need a better solution for this when multi-db stuff is
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# supported. It's the only class-reference to the module-level
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# connection variable.
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self.connection = connection
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def get_meta(self):
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"""
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Returns the Options instance (the model._meta) from which to start
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processing. Normally, this is self.model._meta, but it can change.
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"""
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if self.start_meta:
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return self.start_meta
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return self.model._meta
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def quote_name_unless_alias(self, name):
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"""
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A wrapper around connection.ops.quote_name that doesn't quote aliases
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for table names. This avoids problems with some SQL dialects that treat
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quoted strings specially (e.g. PostgreSQL).
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"""
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if name in self.quote_cache:
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return self.quote_cache[name]
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if ((name in self.alias_map and name not in self.table_map) or
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name in self.extra_select):
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self.quote_cache[name] = name
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return name
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r = self.connection.ops.quote_name(name)
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self.quote_cache[name] = r
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return r
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def clone(self, klass=None, **kwargs):
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"""
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Creates a copy of the current instance. The 'kwargs' parameter can be
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used by clients to update attributes after copying has taken place.
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"""
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obj = Empty()
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obj.__class__ = klass or self.__class__
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obj.model = self.model
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obj.connection = self.connection
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obj.alias_refcount = self.alias_refcount.copy()
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obj.alias_map = self.alias_map.copy()
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obj.table_map = self.table_map.copy()
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obj.join_map = self.join_map.copy()
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obj.rev_join_map = self.rev_join_map.copy()
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obj.quote_cache = {}
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obj.default_cols = self.default_cols
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obj.default_ordering = self.default_ordering
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obj.standard_ordering = self.standard_ordering
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obj.ordering_aliases = []
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obj.start_meta = self.start_meta
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obj.select_fields = self.select_fields[:]
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obj.related_select_fields = self.related_select_fields[:]
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obj.select = self.select[:]
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obj.tables = self.tables[:]
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obj.where = deepcopy(self.where)
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obj.where_class = self.where_class
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obj.group_by = self.group_by[:]
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obj.having = self.having[:]
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obj.order_by = self.order_by[:]
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obj.low_mark, obj.high_mark = self.low_mark, self.high_mark
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obj.distinct = self.distinct
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obj.select_related = self.select_related
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obj.related_select_cols = []
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obj.max_depth = self.max_depth
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obj.extra_select = self.extra_select.copy()
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obj.extra_select_params = self.extra_select_params
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obj.extra_tables = self.extra_tables
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obj.extra_where = self.extra_where
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obj.extra_params = self.extra_params
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obj.extra_order_by = self.extra_order_by
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obj.__dict__.update(kwargs)
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if hasattr(obj, '_setup_query'):
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obj._setup_query()
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return obj
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def results_iter(self):
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"""
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Returns an iterator over the results from executing this query.
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"""
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resolve_columns = hasattr(self, 'resolve_columns')
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if resolve_columns:
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if self.select_fields:
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fields = self.select_fields + self.related_select_fields
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else:
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fields = self.model._meta.fields
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for rows in self.execute_sql(MULTI):
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for row in rows:
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if resolve_columns:
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row = self.resolve_columns(row, fields)
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yield row
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def get_count(self):
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"""
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Performs a COUNT() query using the current filter constraints.
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"""
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from subqueries import CountQuery
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obj = self.clone()
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obj.clear_ordering(True)
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obj.clear_limits()
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obj.select_related = False
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obj.related_select_cols = []
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obj.related_select_fields = []
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if obj.distinct and len(obj.select) > 1:
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obj = self.clone(CountQuery, _query=obj, where=self.where_class(),
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distinct=False)
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obj.select = []
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obj.extra_select = {}
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obj.add_count_column()
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data = obj.execute_sql(SINGLE)
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if not data:
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return 0
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number = data[0]
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# Apply offset and limit constraints manually, since using LIMIT/OFFSET
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# in SQL (in variants that provide them) doesn't change the COUNT
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# output.
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number = max(0, number - self.low_mark)
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if self.high_mark:
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number = min(number, self.high_mark - self.low_mark)
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return number
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def as_sql(self, with_limits=True, with_col_aliases=False):
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"""
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Creates the SQL for this query. Returns the SQL string and list of
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parameters.
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If 'with_limits' is False, any limit/offset information is not included
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in the query.
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"""
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self.pre_sql_setup()
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out_cols = self.get_columns(with_col_aliases)
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ordering = self.get_ordering()
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# This must come after 'select' and 'ordering' -- see docstring of
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# get_from_clause() for details.
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from_, f_params = self.get_from_clause()
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where, w_params = self.where.as_sql(qn=self.quote_name_unless_alias)
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params = list(self.extra_select_params)
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result = ['SELECT']
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if self.distinct:
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result.append('DISTINCT')
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result.append(', '.join(out_cols + self.ordering_aliases))
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result.append('FROM')
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result.extend(from_)
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params.extend(f_params)
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if where:
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result.append('WHERE %s' % where)
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params.extend(w_params)
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if self.extra_where:
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if not where:
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result.append('WHERE')
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else:
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result.append('AND')
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result.append(' AND '.join(self.extra_where))
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if self.group_by:
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grouping = self.get_grouping()
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result.append('GROUP BY %s' % ', '.join(grouping))
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if ordering:
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result.append('ORDER BY %s' % ', '.join(ordering))
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# FIXME: Pull this out to make life easier for Oracle et al.
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if with_limits:
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if self.high_mark:
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result.append('LIMIT %d' % (self.high_mark - self.low_mark))
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if self.low_mark:
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if not self.high_mark:
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val = self.connection.ops.no_limit_value()
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if val:
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result.append('LIMIT %d' % val)
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result.append('OFFSET %d' % self.low_mark)
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params.extend(self.extra_params)
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return ' '.join(result), tuple(params)
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def combine(self, rhs, connector):
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"""
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Merge the 'rhs' query into the current one (with any 'rhs' effects
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being applied *after* (that is, "to the right of") anything in the
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current query. 'rhs' is not modified during a call to this function.
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The 'connector' parameter describes how to connect filters from the
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'rhs' query.
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"""
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assert self.model == rhs.model, \
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"Cannot combine queries on two different base models."
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assert self.can_filter(), \
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"Cannot combine queries once a slice has been taken."
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assert self.distinct == rhs.distinct, \
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"Cannot combine a unique query with a non-unique query."
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# Work out how to relabel the rhs aliases, if necessary.
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change_map = {}
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used = set()
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conjunction = (connector == AND)
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first = True
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for alias in rhs.tables:
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if not rhs.alias_refcount[alias]:
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# An unused alias.
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continue
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promote = (rhs.alias_map[alias][JOIN_TYPE] == self.LOUTER)
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new_alias = self.join(rhs.rev_join_map[alias],
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(conjunction and not first), used, promote, not conjunction)
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used.add(new_alias)
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change_map[alias] = new_alias
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first = False
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# So that we don't exclude valid results in an "or" query combination,
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# the first join that is exclusive to the lhs (self) must be converted
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# to an outer join.
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if not conjunction:
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for alias in self.tables[1:]:
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if self.alias_refcount[alias] == 1:
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self.promote_alias(alias, True)
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break
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# Now relabel a copy of the rhs where-clause and add it to the current
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# one.
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if rhs.where:
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w = deepcopy(rhs.where)
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w.relabel_aliases(change_map)
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if not self.where:
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# Since 'self' matches everything, add an explicit "include
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# everything" where-constraint so that connections between the
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# where clauses won't exclude valid results.
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self.where.add(EverythingNode(), AND)
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elif self.where:
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# rhs has an empty where clause.
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w = self.where_class()
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w.add(EverythingNode(), AND)
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else:
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w = self.where_class()
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self.where.add(w, connector)
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# Selection columns and extra extensions are those provided by 'rhs'.
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self.select = []
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for col in rhs.select:
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if isinstance(col, (list, tuple)):
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self.select.append((change_map.get(col[0], col[0]), col[1]))
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else:
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item = deepcopy(col)
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item.relabel_aliases(change_map)
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self.select.append(item)
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self.select_fields = rhs.select_fields[:]
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self.extra_select = rhs.extra_select.copy()
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self.extra_tables = rhs.extra_tables
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self.extra_where = rhs.extra_where
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self.extra_params = rhs.extra_params
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# Ordering uses the 'rhs' ordering, unless it has none, in which case
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# the current ordering is used.
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self.order_by = rhs.order_by and rhs.order_by[:] or self.order_by
|
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self.extra_order_by = rhs.extra_order_by or self.extra_order_by
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def pre_sql_setup(self):
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"""
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Does any necessary class setup immediately prior to producing SQL. This
|
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is for things that can't necessarily be done in __init__ because we
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might not have all the pieces in place at that time.
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"""
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if not self.tables:
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self.join((None, self.model._meta.db_table, None, None))
|
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if self.select_related and not self.related_select_cols:
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self.fill_related_selections()
|
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def get_columns(self, with_aliases=False):
|
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"""
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Return the list of columns to use in the select statement. If no
|
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columns have been specified, returns all columns relating to fields in
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the model.
|
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If 'with_aliases' is true, any column names that are duplicated
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(without the table names) are given unique aliases. This is needed in
|
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some cases to avoid ambiguitity with nested queries.
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"""
|
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qn = self.quote_name_unless_alias
|
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qn2 = self.connection.ops.quote_name
|
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result = ['(%s) AS %s' % (col, qn2(alias)) for alias, col in self.extra_select.iteritems()]
|
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aliases = set(self.extra_select.keys())
|
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if with_aliases:
|
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col_aliases = aliases.copy()
|
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else:
|
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col_aliases = set()
|
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if self.select:
|
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for col in self.select:
|
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if isinstance(col, (list, tuple)):
|
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r = '%s.%s' % (qn(col[0]), qn(col[1]))
|
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if with_aliases and col[1] in col_aliases:
|
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c_alias = 'Col%d' % len(col_aliases)
|
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result.append('%s AS %s' % (r, c_alias))
|
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aliases.add(c_alias)
|
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col_aliases.add(c_alias)
|
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else:
|
|
result.append(r)
|
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aliases.add(r)
|
|
col_aliases.add(col[1])
|
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else:
|
|
result.append(col.as_sql(quote_func=qn))
|
|
if hasattr(col, 'alias'):
|
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aliases.add(col.alias)
|
|
col_aliases.add(col.alias)
|
|
elif self.default_cols:
|
|
cols, new_aliases = self.get_default_columns(with_aliases,
|
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col_aliases)
|
|
result.extend(cols)
|
|
aliases.update(new_aliases)
|
|
for table, col in self.related_select_cols:
|
|
r = '%s.%s' % (qn(table), qn(col))
|
|
if with_aliases and col in col_aliases:
|
|
c_alias = 'Col%d' % len(col_aliases)
|
|
result.append('%s AS %s' % (r, c_alias))
|
|
aliases.add(c_alias)
|
|
col_aliases.add(c_alias)
|
|
else:
|
|
result.append(r)
|
|
aliases.add(r)
|
|
col_aliases.add(col)
|
|
|
|
self._select_aliases = aliases
|
|
return result
|
|
|
|
def get_default_columns(self, with_aliases=False, col_aliases=None):
|
|
"""
|
|
Computes the default columns for selecting every field in the base
|
|
model.
|
|
|
|
Returns a list of strings, quoted appropriately for use in SQL
|
|
directly, as well as a set of aliases used in the select statement.
|
|
"""
|
|
result = []
|
|
table_alias = self.tables[0]
|
|
root_pk = self.model._meta.pk.column
|
|
seen = {None: table_alias}
|
|
qn = self.quote_name_unless_alias
|
|
qn2 = self.connection.ops.quote_name
|
|
aliases = set()
|
|
for field, model in self.model._meta.get_fields_with_model():
|
|
try:
|
|
alias = seen[model]
|
|
except KeyError:
|
|
alias = self.join((table_alias, model._meta.db_table,
|
|
root_pk, model._meta.pk.column))
|
|
seen[model] = alias
|
|
if with_aliases and field.column in col_aliases:
|
|
c_alias = 'Col%d' % len(col_aliases)
|
|
result.append('%s.%s AS %s' % (qn(alias),
|
|
qn2(field.column), c_alias))
|
|
col_aliases.add(c_alias)
|
|
aliases.add(c_alias)
|
|
else:
|
|
r = '%s.%s' % (qn(alias), qn2(field.column))
|
|
result.append(r)
|
|
aliases.add(r)
|
|
if with_aliases:
|
|
col_aliases.add(field.column)
|
|
return result, aliases
|
|
|
|
def get_from_clause(self):
|
|
"""
|
|
Returns a list of strings that are joined together to go after the
|
|
"FROM" part of the query, as well as a list any extra parameters that
|
|
need to be included. Sub-classes, can override this to create a
|
|
from-clause via a "select", for example (e.g. CountQuery).
|
|
|
|
This should only be called after any SQL construction methods that
|
|
might change the tables we need. This means the select columns and
|
|
ordering must be done first.
|
|
"""
|
|
result = []
|
|
qn = self.quote_name_unless_alias
|
|
qn2 = self.connection.ops.quote_name
|
|
first = True
|
|
for alias in self.tables:
|
|
if not self.alias_refcount[alias]:
|
|
continue
|
|
try:
|
|
name, alias, join_type, lhs, lhs_col, col, nullable = self.alias_map[alias]
|
|
except KeyError:
|
|
# Extra tables can end up in self.tables, but not in the
|
|
# alias_map if they aren't in a join. That's OK. We skip them.
|
|
continue
|
|
alias_str = (alias != name and ' %s' % alias or '')
|
|
if join_type and not first:
|
|
result.append('%s %s%s ON (%s.%s = %s.%s)'
|
|
% (join_type, qn(name), alias_str, qn(lhs),
|
|
qn2(lhs_col), qn(alias), qn2(col)))
|
|
else:
|
|
connector = not first and ', ' or ''
|
|
result.append('%s%s%s' % (connector, qn(name), alias_str))
|
|
first = False
|
|
for t in self.extra_tables:
|
|
alias, unused = self.table_alias(t)
|
|
if alias not in self.alias_map:
|
|
connector = not first and ', ' or ''
|
|
result.append('%s%s' % (connector, qn(alias)))
|
|
first = False
|
|
return result, []
|
|
|
|
def get_grouping(self):
|
|
"""
|
|
Returns a tuple representing the SQL elements in the "group by" clause.
|
|
"""
|
|
qn = self.quote_name_unless_alias
|
|
result = []
|
|
for col in self.group_by:
|
|
if isinstance(col, (list, tuple)):
|
|
result.append('%s.%s' % (qn(col[0]), qn(col[1])))
|
|
elif hasattr(col, 'as_sql'):
|
|
result.append(col.as_sql(qn))
|
|
else:
|
|
result.append(str(col))
|
|
return result
|
|
|
|
def get_ordering(self):
|
|
"""
|
|
Returns list representing the SQL elements in the "order by" clause.
|
|
Also sets the ordering_aliases attribute on this instance to a list of
|
|
extra aliases needed in the select.
|
|
|
|
Determining the ordering SQL can change the tables we need to include,
|
|
so this should be run *before* get_from_clause().
|
|
"""
|
|
if self.extra_order_by:
|
|
ordering = self.extra_order_by
|
|
elif not self.default_ordering:
|
|
ordering = []
|
|
else:
|
|
ordering = self.order_by or self.model._meta.ordering
|
|
qn = self.quote_name_unless_alias
|
|
qn2 = self.connection.ops.quote_name
|
|
distinct = self.distinct
|
|
select_aliases = self._select_aliases
|
|
result = []
|
|
ordering_aliases = []
|
|
if self.standard_ordering:
|
|
asc, desc = ORDER_DIR['ASC']
|
|
else:
|
|
asc, desc = ORDER_DIR['DESC']
|
|
for field in ordering:
|
|
if field == '?':
|
|
result.append(self.connection.ops.random_function_sql())
|
|
continue
|
|
if isinstance(field, int):
|
|
if field < 0:
|
|
order = desc
|
|
field = -field
|
|
else:
|
|
order = asc
|
|
result.append('%s %s' % (field, order))
|
|
continue
|
|
if '.' in field:
|
|
# This came in through an extra(order_by=...) addition. Pass it
|
|
# on verbatim.
|
|
col, order = get_order_dir(field, asc)
|
|
table, col = col.split('.', 1)
|
|
elt = '%s.%s' % (qn(table), col)
|
|
if not distinct or elt in select_aliases:
|
|
result.append('%s %s' % (elt, order))
|
|
elif get_order_dir(field)[0] not in self.extra_select:
|
|
# 'col' is of the form 'field' or 'field1__field2' or
|
|
# '-field1__field2__field', etc.
|
|
for table, col, order in self.find_ordering_name(field,
|
|
self.model._meta, default_order=asc):
|
|
elt = '%s.%s' % (qn(table), qn2(col))
|
|
if distinct and elt not in select_aliases:
|
|
ordering_aliases.append(elt)
|
|
result.append('%s %s' % (elt, order))
|
|
else:
|
|
col, order = get_order_dir(field, asc)
|
|
elt = qn(col)
|
|
if distinct and elt not in select_aliases:
|
|
ordering_aliases.append(elt)
|
|
result.append('%s %s' % (elt, order))
|
|
self.ordering_aliases = ordering_aliases
|
|
return result
|
|
|
|
def find_ordering_name(self, name, opts, alias=None, default_order='ASC',
|
|
already_seen=None):
|
|
"""
|
|
Returns the table alias (the name might be ambiguous, the alias will
|
|
not be) and column name for ordering by the given 'name' parameter.
|
|
The 'name' is of the form 'field1__field2__...__fieldN'.
|
|
"""
|
|
name, order = get_order_dir(name, default_order)
|
|
pieces = name.split(LOOKUP_SEP)
|
|
if not alias:
|
|
alias = self.get_initial_alias()
|
|
field, target, opts, joins, last = self.setup_joins(pieces, opts,
|
|
alias, False)
|
|
alias = joins[-1]
|
|
col = target.column
|
|
|
|
# If we get to this point and the field is a relation to another model,
|
|
# append the default ordering for that model.
|
|
if field.rel and len(joins) > 1 and opts.ordering:
|
|
# Firstly, avoid infinite loops.
|
|
if not already_seen:
|
|
already_seen = set()
|
|
join_tuple = tuple([self.alias_map[j][TABLE_NAME] for j in joins])
|
|
if join_tuple in already_seen:
|
|
raise FieldError('Infinite loop caused by ordering.')
|
|
already_seen.add(join_tuple)
|
|
|
|
results = []
|
|
for item in opts.ordering:
|
|
results.extend(self.find_ordering_name(item, opts, alias,
|
|
order, already_seen))
|
|
return results
|
|
|
|
if alias:
|
|
# We have to do the same "final join" optimisation as in
|
|
# add_filter, since the final column might not otherwise be part of
|
|
# the select set (so we can't order on it).
|
|
join = self.alias_map[alias]
|
|
if col == join[RHS_JOIN_COL]:
|
|
self.unref_alias(alias)
|
|
alias = join[LHS_ALIAS]
|
|
col = join[LHS_JOIN_COL]
|
|
return [(alias, col, order)]
|
|
|
|
def table_alias(self, table_name, create=False):
|
|
"""
|
|
Returns a table alias for the given table_name and whether this is a
|
|
new alias or not.
|
|
|
|
If 'create' is true, a new alias is always created. Otherwise, the
|
|
most recently created alias for the table (if one exists) is reused.
|
|
"""
|
|
current = self.table_map.get(table_name)
|
|
if not create and current:
|
|
alias = current[0]
|
|
self.alias_refcount[alias] += 1
|
|
return alias, False
|
|
|
|
# Create a new alias for this table.
|
|
if current:
|
|
alias = '%s%d' % (self.alias_prefix, len(self.alias_map) + 1)
|
|
current.append(alias)
|
|
else:
|
|
# The first occurence of a table uses the table name directly.
|
|
alias = table_name
|
|
self.table_map[alias] = [alias]
|
|
self.alias_refcount[alias] = 1
|
|
#self.alias_map[alias] = None
|
|
self.tables.append(alias)
|
|
return alias, True
|
|
|
|
def ref_alias(self, alias):
|
|
""" Increases the reference count for this alias. """
|
|
self.alias_refcount[alias] += 1
|
|
|
|
def unref_alias(self, alias):
|
|
""" Decreases the reference count for this alias. """
|
|
self.alias_refcount[alias] -= 1
|
|
|
|
def promote_alias(self, alias, unconditional=False):
|
|
"""
|
|
Promotes the join type of an alias to an outer join if it's possible
|
|
for the join to contain NULL values on the left. If 'unconditional' is
|
|
False, the join is only promoted if it is nullable, otherwise it is
|
|
always promoted.
|
|
"""
|
|
if ((unconditional or self.alias_map[alias][NULLABLE]) and
|
|
self.alias_map[alias] != self.LOUTER):
|
|
data = list(self.alias_map[alias])
|
|
data[JOIN_TYPE] = self.LOUTER
|
|
self.alias_map[alias] = tuple(data)
|
|
|
|
def change_aliases(self, change_map):
|
|
"""
|
|
Changes the aliases in change_map (which maps old-alias -> new-alias),
|
|
relabelling any references to them in select columns and the where
|
|
clause.
|
|
"""
|
|
assert set(change_map.keys()).intersection(set(change_map.values())) == set()
|
|
|
|
# 1. Update references in "select" and "where".
|
|
self.where.relabel_aliases(change_map)
|
|
for pos, col in enumerate(self.select):
|
|
if isinstance(col, (list, tuple)):
|
|
self.select[pos] = (change_map.get(old_alias, old_alias), col[1])
|
|
else:
|
|
col.relabel_aliases(change_map)
|
|
|
|
# 2. Rename the alias in the internal table/alias datastructures.
|
|
for old_alias, new_alias in change_map.iteritems():
|
|
alias_data = list(self.alias_map[old_alias])
|
|
alias_data[RHS_ALIAS] = new_alias
|
|
|
|
t = self.rev_join_map[old_alias]
|
|
data = list(self.join_map[t])
|
|
data[data.index(old_alias)] = new_alias
|
|
self.join_map[t] = tuple(data)
|
|
self.rev_join_map[new_alias] = t
|
|
del self.rev_join_map[old_alias]
|
|
self.alias_refcount[new_alias] = self.alias_refcount[old_alias]
|
|
del self.alias_refcount[old_alias]
|
|
self.alias_map[new_alias] = tuple(alias_data)
|
|
del self.alias_map[old_alias]
|
|
|
|
table_aliases = self.table_map[alias_data[TABLE_NAME]]
|
|
for pos, alias in enumerate(table_aliases):
|
|
if alias == old_alias:
|
|
table_aliases[pos] = new_alias
|
|
break
|
|
for pos, alias in enumerate(self.tables):
|
|
if alias == old_alias:
|
|
self.tables[pos] = new_alias
|
|
break
|
|
|
|
# 3. Update any joins that refer to the old alias.
|
|
for alias, data in self.alias_map.iteritems():
|
|
lhs = data[LHS_ALIAS]
|
|
if lhs in change_map:
|
|
data = list(data)
|
|
data[LHS_ALIAS] = change_map[lhs]
|
|
self.alias_map[alias] = tuple(data)
|
|
|
|
def bump_prefix(self, exceptions=()):
|
|
"""
|
|
Changes the alias prefix to the next letter in the alphabet and
|
|
relabels all the aliases. Even tables that previously had no alias will
|
|
get an alias after this call (it's mostly used for nested queries and
|
|
the outer query will already be using the non-aliased table name).
|
|
|
|
Subclasses who create their own prefix should override this method to
|
|
produce a similar result (a new prefix and relabelled aliases).
|
|
|
|
The 'exceptions' parameter is a container that holds alias names which
|
|
should not be changed.
|
|
"""
|
|
assert ord(self.alias_prefix) < ord('Z')
|
|
self.alias_prefix = chr(ord(self.alias_prefix) + 1)
|
|
change_map = {}
|
|
prefix = self.alias_prefix
|
|
for pos, alias in enumerate(self.tables):
|
|
if alias in exceptions:
|
|
continue
|
|
new_alias = '%s%d' % (prefix, pos)
|
|
change_map[alias] = new_alias
|
|
self.tables[pos] = new_alias
|
|
self.change_aliases(change_map)
|
|
|
|
def get_initial_alias(self):
|
|
"""
|
|
Returns the first alias for this query, after increasing its reference
|
|
count.
|
|
"""
|
|
if self.tables:
|
|
alias = self.tables[0]
|
|
self.ref_alias(alias)
|
|
else:
|
|
alias = self.join((None, self.model._meta.db_table, None, None))
|
|
return alias
|
|
|
|
def count_active_tables(self):
|
|
"""
|
|
Returns the number of tables in this query with a non-zero reference
|
|
count.
|
|
"""
|
|
return len([1 for count in self.alias_refcount.itervalues() if count])
|
|
|
|
def join(self, connection, always_create=False, exclusions=(),
|
|
promote=False, outer_if_first=False, nullable=False, reuse=None):
|
|
"""
|
|
Returns an alias for the join in 'connection', either reusing an
|
|
existing alias for that join or creating a new one. 'connection' is a
|
|
tuple (lhs, table, lhs_col, col) where 'lhs' is either an existing
|
|
table alias or a table name. The join correspods to the SQL equivalent
|
|
of::
|
|
|
|
lhs.lhs_col = table.col
|
|
|
|
If 'always_create' is True and 'reuse' is None, a new alias is always
|
|
created, regardless of whether one already exists or not. Otherwise
|
|
'reuse' must be a set and a new join is created unless one of the
|
|
aliases in `reuse` can be used.
|
|
|
|
If 'exclusions' is specified, it is something satisfying the container
|
|
protocol ("foo in exclusions" must work) and specifies a list of
|
|
aliases that should not be returned, even if they satisfy the join.
|
|
|
|
If 'promote' is True, the join type for the alias will be LOUTER (if
|
|
the alias previously existed, the join type will be promoted from INNER
|
|
to LOUTER, if necessary).
|
|
|
|
If 'outer_if_first' is True and a new join is created, it will have the
|
|
LOUTER join type. This is used when joining certain types of querysets
|
|
and Q-objects together.
|
|
|
|
If 'nullable' is True, the join can potentially involve NULL values and
|
|
is a candidate for promotion (to "left outer") when combining querysets.
|
|
"""
|
|
lhs, table, lhs_col, col = connection
|
|
if lhs in self.alias_map:
|
|
lhs_table = self.alias_map[lhs][TABLE_NAME]
|
|
else:
|
|
lhs_table = lhs
|
|
|
|
if reuse and always_create and table in self.table_map:
|
|
# Convert the 'reuse' to case to be "exclude everything but the
|
|
# reusable set for this table".
|
|
exclusions = set(self.table_map[table]).difference(reuse)
|
|
always_create = False
|
|
t_ident = (lhs_table, table, lhs_col, col)
|
|
if not always_create:
|
|
for alias in self.join_map.get(t_ident, ()):
|
|
if alias not in exclusions:
|
|
self.ref_alias(alias)
|
|
if promote:
|
|
self.promote_alias(alias)
|
|
return alias
|
|
|
|
# No reuse is possible, so we need a new alias.
|
|
alias, _ = self.table_alias(table, True)
|
|
if not lhs:
|
|
# Not all tables need to be joined to anything. No join type
|
|
# means the later columns are ignored.
|
|
join_type = None
|
|
elif promote or outer_if_first:
|
|
join_type = self.LOUTER
|
|
else:
|
|
join_type = self.INNER
|
|
join = (table, alias, join_type, lhs, lhs_col, col, nullable)
|
|
self.alias_map[alias] = join
|
|
if t_ident in self.join_map:
|
|
self.join_map[t_ident] += (alias,)
|
|
else:
|
|
self.join_map[t_ident] = (alias,)
|
|
self.rev_join_map[alias] = t_ident
|
|
return alias
|
|
|
|
def fill_related_selections(self, opts=None, root_alias=None, cur_depth=1,
|
|
used=None, requested=None, restricted=None, nullable=None):
|
|
"""
|
|
Fill in the information needed for a select_related query. The current
|
|
depth is measured as the number of connections away from the root model
|
|
(for example, cur_depth=1 means we are looking at models with direct
|
|
connections to the root model).
|
|
"""
|
|
if not restricted and self.max_depth and cur_depth > self.max_depth:
|
|
# We've recursed far enough; bail out.
|
|
return
|
|
if not opts:
|
|
opts = self.get_meta()
|
|
root_alias = self.get_initial_alias()
|
|
self.related_select_cols = []
|
|
self.related_select_fields = []
|
|
if not used:
|
|
used = set()
|
|
|
|
# Setup for the case when only particular related fields should be
|
|
# included in the related selection.
|
|
if requested is None and restricted is not False:
|
|
if isinstance(self.select_related, dict):
|
|
requested = self.select_related
|
|
restricted = True
|
|
else:
|
|
restricted = False
|
|
|
|
for f, model in opts.get_fields_with_model():
|
|
if (not f.rel or (restricted and f.name not in requested) or
|
|
(not restricted and f.null) or f.rel.parent_link):
|
|
continue
|
|
table = f.rel.to._meta.db_table
|
|
if nullable or f.null:
|
|
promote = True
|
|
else:
|
|
promote = False
|
|
if model:
|
|
int_opts = opts
|
|
alias = root_alias
|
|
for int_model in opts.get_base_chain(model):
|
|
lhs_col = int_opts.parents[int_model].column
|
|
int_opts = int_model._meta
|
|
alias = self.join((alias, int_opts.db_table, lhs_col,
|
|
int_opts.pk.column), exclusions=used,
|
|
promote=promote)
|
|
else:
|
|
alias = root_alias
|
|
alias = self.join((alias, table, f.column,
|
|
f.rel.get_related_field().column), exclusions=used,
|
|
promote=promote)
|
|
used.add(alias)
|
|
self.related_select_cols.extend([(alias, f2.column)
|
|
for f2 in f.rel.to._meta.fields])
|
|
self.related_select_fields.extend(f.rel.to._meta.fields)
|
|
if restricted:
|
|
next = requested.get(f.name, {})
|
|
else:
|
|
next = False
|
|
if f.null is not None:
|
|
new_nullable = f.null
|
|
else:
|
|
new_nullable = None
|
|
self.fill_related_selections(f.rel.to._meta, alias, cur_depth + 1,
|
|
used, next, restricted, new_nullable)
|
|
|
|
def add_filter(self, filter_expr, connector=AND, negate=False, trim=False,
|
|
can_reuse=None):
|
|
"""
|
|
Add a single filter to the query. The 'filter_expr' is a pair:
|
|
(filter_string, value). E.g. ('name__contains', 'fred')
|
|
|
|
If 'negate' is True, this is an exclude() filter. It's important to
|
|
note that this method does not negate anything in the where-clause
|
|
object when inserting the filter constraints. This is because negated
|
|
filters often require multiple calls to add_filter() and the negation
|
|
should only happen once. So the caller is responsible for this (the
|
|
caller will normally be add_q(), so that as an example).
|
|
|
|
If 'trim' is True, we automatically trim the final join group (used
|
|
internally when constructing nested queries).
|
|
|
|
If 'can_reuse' is a set, we are processing a component of a
|
|
multi-component filter (e.g. filter(Q1, Q2)). In this case, 'can_reuse'
|
|
will be a set of table aliases that can be reused in this filter, even
|
|
if we would otherwise force the creation of new aliases for a join
|
|
(needed for nested Q-filters). The set is updated by this method.
|
|
"""
|
|
arg, value = filter_expr
|
|
parts = arg.split(LOOKUP_SEP)
|
|
if not parts:
|
|
raise FieldError("Cannot parse keyword query %r" % arg)
|
|
|
|
# Work out the lookup type and remove it from 'parts', if necessary.
|
|
if len(parts) == 1 or parts[-1] not in self.query_terms:
|
|
lookup_type = 'exact'
|
|
else:
|
|
lookup_type = parts.pop()
|
|
|
|
# Interpret '__exact=None' as the sql 'is NULL'; otherwise, reject all
|
|
# uses of None as a query value.
|
|
if value is None:
|
|
if lookup_type != 'exact':
|
|
raise ValueError("Cannot use None as a query value")
|
|
lookup_type = 'isnull'
|
|
value = True
|
|
elif callable(value):
|
|
value = value()
|
|
|
|
opts = self.get_meta()
|
|
alias = self.get_initial_alias()
|
|
allow_many = trim or not negate
|
|
|
|
try:
|
|
field, target, opts, join_list, last = self.setup_joins(parts, opts,
|
|
alias, True, allow_many, can_reuse=can_reuse)
|
|
except MultiJoin, e:
|
|
self.split_exclude(filter_expr, LOOKUP_SEP.join(parts[:e.level]))
|
|
return
|
|
final = len(join_list)
|
|
penultimate = last.pop()
|
|
if penultimate == final:
|
|
penultimate = last.pop()
|
|
if trim and len(join_list) > 1:
|
|
extra = join_list[penultimate:]
|
|
join_list = join_list[:penultimate]
|
|
final = penultimate
|
|
penultimate = last.pop()
|
|
col = self.alias_map[extra[0]][LHS_JOIN_COL]
|
|
for alias in extra:
|
|
self.unref_alias(alias)
|
|
else:
|
|
col = target.column
|
|
alias = join_list[-1]
|
|
|
|
if final > 1:
|
|
# An optimization: if the final join is against the same column as
|
|
# we are comparing against, we can go back one step in the join
|
|
# chain and compare against the lhs of the join instead. The result
|
|
# (potentially) involves one less table join.
|
|
join = self.alias_map[alias]
|
|
if col == join[RHS_JOIN_COL]:
|
|
self.unref_alias(alias)
|
|
alias = join[LHS_ALIAS]
|
|
col = join[LHS_JOIN_COL]
|
|
join_list = join_list[:-1]
|
|
final -= 1
|
|
if final == penultimate:
|
|
penultimate = last.pop()
|
|
|
|
if (lookup_type == 'isnull' and value is True and not negate and
|
|
final > 1):
|
|
# If the comparison is against NULL, we need to use a left outer
|
|
# join when connecting to the previous model. We make that
|
|
# adjustment here. We don't do this unless needed as it's less
|
|
# efficient at the database level.
|
|
self.promote_alias(join_list[penultimate])
|
|
|
|
if connector == OR:
|
|
# Some joins may need to be promoted when adding a new filter to a
|
|
# disjunction. We walk the list of new joins and where it diverges
|
|
# from any previous joins (ref count is 1 in the table list), we
|
|
# make the new additions (and any existing ones not used in the new
|
|
# join list) an outer join.
|
|
join_it = iter(join_list)
|
|
table_it = iter(self.tables)
|
|
join_it.next(), table_it.next()
|
|
for join in join_it:
|
|
table = table_it.next()
|
|
if join == table and self.alias_refcount[join] > 1:
|
|
continue
|
|
self.promote_alias(join)
|
|
if table != join:
|
|
self.promote_alias(table)
|
|
break
|
|
for join in join_it:
|
|
self.promote_alias(join)
|
|
for table in table_it:
|
|
# Some of these will have been promoted from the join_list, but
|
|
# that's harmless.
|
|
self.promote_alias(table)
|
|
|
|
self.where.add((alias, col, field, lookup_type, value), connector)
|
|
if negate:
|
|
for alias in join_list:
|
|
self.promote_alias(alias)
|
|
if final > 1 and lookup_type != 'isnull':
|
|
for alias in join_list:
|
|
if self.alias_map[alias] == self.LOUTER:
|
|
j_col = self.alias_map[alias][RHS_JOIN_COL]
|
|
entry = Node([(alias, j_col, None, 'isnull', True)])
|
|
entry.negate()
|
|
self.where.add(entry, AND)
|
|
break
|
|
if can_reuse is not None:
|
|
can_reuse.update(join_list)
|
|
|
|
def add_q(self, q_object, used_aliases=None):
|
|
"""
|
|
Adds a Q-object to the current filter.
|
|
|
|
Can also be used to add anything that has an 'add_to_query()' method.
|
|
"""
|
|
if used_aliases is None:
|
|
used_aliases = set()
|
|
if hasattr(q_object, 'add_to_query'):
|
|
# Complex custom objects are responsible for adding themselves.
|
|
q_object.add_to_query(self, used_aliases)
|
|
return
|
|
|
|
if self.where and q_object.connector != AND and len(q_object) > 1:
|
|
self.where.start_subtree(AND)
|
|
subtree = True
|
|
else:
|
|
subtree = False
|
|
connector = AND
|
|
for child in q_object.children:
|
|
if isinstance(child, Node):
|
|
self.where.start_subtree(connector)
|
|
self.add_q(child, used_aliases)
|
|
self.where.end_subtree()
|
|
else:
|
|
self.add_filter(child, connector, q_object.negated,
|
|
can_reuse=used_aliases)
|
|
connector = q_object.connector
|
|
if q_object.negated:
|
|
self.where.negate()
|
|
if subtree:
|
|
self.where.end_subtree()
|
|
|
|
def setup_joins(self, names, opts, alias, dupe_multis, allow_many=True,
|
|
allow_explicit_fk=False, can_reuse=None):
|
|
"""
|
|
Compute the necessary table joins for the passage through the fields
|
|
given in 'names'. 'opts' is the Options class for the current model
|
|
(which gives the table we are joining to), 'alias' is the alias for the
|
|
table we are joining to. If dupe_multis is True, any many-to-many or
|
|
many-to-one joins will always create a new alias (necessary for
|
|
disjunctive filters).
|
|
|
|
Returns the final field involved in the join, the target database
|
|
column (used for any 'where' constraint), the final 'opts' value and the
|
|
list of tables joined.
|
|
"""
|
|
joins = [alias]
|
|
last = [0]
|
|
for pos, name in enumerate(names):
|
|
last.append(len(joins))
|
|
if name == 'pk':
|
|
name = opts.pk.name
|
|
|
|
try:
|
|
field, model, direct, m2m = opts.get_field_by_name(name)
|
|
except FieldDoesNotExist:
|
|
for f in opts.fields:
|
|
if allow_explicit_fk and name == f.attname:
|
|
# XXX: A hack to allow foo_id to work in values() for
|
|
# backwards compatibility purposes. If we dropped that
|
|
# feature, this could be removed.
|
|
field, model, direct, m2m = opts.get_field_by_name(f.name)
|
|
break
|
|
else:
|
|
names = opts.get_all_field_names()
|
|
raise FieldError("Cannot resolve keyword %r into field. "
|
|
"Choices are: %s" % (name, ", ".join(names)))
|
|
if not allow_many and (m2m or not direct):
|
|
for alias in joins:
|
|
self.unref_alias(alias)
|
|
raise MultiJoin(pos + 1)
|
|
if model:
|
|
# The field lives on a base class of the current model.
|
|
alias_list = []
|
|
for int_model in opts.get_base_chain(model):
|
|
lhs_col = opts.parents[int_model].column
|
|
opts = int_model._meta
|
|
alias = self.join((alias, opts.db_table, lhs_col,
|
|
opts.pk.column), exclusions=joins)
|
|
joins.append(alias)
|
|
cached_data = opts._join_cache.get(name)
|
|
orig_opts = opts
|
|
|
|
if direct:
|
|
if m2m:
|
|
# Many-to-many field defined on the current model.
|
|
if cached_data:
|
|
(table1, from_col1, to_col1, table2, from_col2,
|
|
to_col2, opts, target) = cached_data
|
|
else:
|
|
table1 = field.m2m_db_table()
|
|
from_col1 = opts.pk.column
|
|
to_col1 = field.m2m_column_name()
|
|
opts = field.rel.to._meta
|
|
table2 = opts.db_table
|
|
from_col2 = field.m2m_reverse_name()
|
|
to_col2 = opts.pk.column
|
|
target = opts.pk
|
|
orig_opts._join_cache[name] = (table1, from_col1,
|
|
to_col1, table2, from_col2, to_col2, opts,
|
|
target)
|
|
|
|
int_alias = self.join((alias, table1, from_col1, to_col1),
|
|
dupe_multis, joins, nullable=True, reuse=can_reuse)
|
|
alias = self.join((int_alias, table2, from_col2, to_col2),
|
|
dupe_multis, joins, nullable=True, reuse=can_reuse)
|
|
joins.extend([int_alias, alias])
|
|
elif field.rel:
|
|
# One-to-one or many-to-one field
|
|
if cached_data:
|
|
(table, from_col, to_col, opts, target) = cached_data
|
|
else:
|
|
opts = field.rel.to._meta
|
|
target = field.rel.get_related_field()
|
|
table = opts.db_table
|
|
from_col = field.column
|
|
to_col = target.column
|
|
orig_opts._join_cache[name] = (table, from_col, to_col,
|
|
opts, target)
|
|
|
|
alias = self.join((alias, table, from_col, to_col),
|
|
exclusions=joins, nullable=field.null)
|
|
joins.append(alias)
|
|
else:
|
|
# Non-relation fields.
|
|
target = field
|
|
break
|
|
else:
|
|
orig_field = field
|
|
field = field.field
|
|
if m2m:
|
|
# Many-to-many field defined on the target model.
|
|
if cached_data:
|
|
(table1, from_col1, to_col1, table2, from_col2,
|
|
to_col2, opts, target) = cached_data
|
|
else:
|
|
table1 = field.m2m_db_table()
|
|
from_col1 = opts.pk.column
|
|
to_col1 = field.m2m_reverse_name()
|
|
opts = orig_field.opts
|
|
table2 = opts.db_table
|
|
from_col2 = field.m2m_column_name()
|
|
to_col2 = opts.pk.column
|
|
target = opts.pk
|
|
orig_opts._join_cache[name] = (table1, from_col1,
|
|
to_col1, table2, from_col2, to_col2, opts,
|
|
target)
|
|
|
|
int_alias = self.join((alias, table1, from_col1, to_col1),
|
|
dupe_multis, joins, nullable=True, reuse=can_reuse)
|
|
alias = self.join((int_alias, table2, from_col2, to_col2),
|
|
dupe_multis, joins, nullable=True, reuse=can_reuse)
|
|
joins.extend([int_alias, alias])
|
|
else:
|
|
# One-to-many field (ForeignKey defined on the target model)
|
|
if cached_data:
|
|
(table, from_col, to_col, opts, target) = cached_data
|
|
else:
|
|
local_field = opts.get_field_by_name(
|
|
field.rel.field_name)[0]
|
|
opts = orig_field.opts
|
|
table = opts.db_table
|
|
from_col = local_field.column
|
|
to_col = field.column
|
|
target = opts.pk
|
|
orig_opts._join_cache[name] = (table, from_col, to_col,
|
|
opts, target)
|
|
|
|
alias = self.join((alias, table, from_col, to_col),
|
|
dupe_multis, joins, nullable=True, reuse=can_reuse)
|
|
joins.append(alias)
|
|
|
|
if pos != len(names) - 1:
|
|
raise FieldError("Join on field %r not permitted." % name)
|
|
|
|
return field, target, opts, joins, last
|
|
|
|
def split_exclude(self, filter_expr, prefix):
|
|
"""
|
|
When doing an exclude against any kind of N-to-many relation, we need
|
|
to use a subquery. This method constructs the nested query, given the
|
|
original exclude filter (filter_expr) and the portion up to the first
|
|
N-to-many relation field.
|
|
"""
|
|
query = Query(self.model, self.connection)
|
|
query.add_filter(filter_expr)
|
|
query.set_start(prefix)
|
|
query.clear_ordering(True)
|
|
self.add_filter(('%s__in' % prefix, query), negate=True, trim=True)
|
|
|
|
def set_limits(self, low=None, high=None):
|
|
"""
|
|
Adjusts the limits on the rows retrieved. We use low/high to set these,
|
|
as it makes it more Pythonic to read and write. When the SQL query is
|
|
created, they are converted to the appropriate offset and limit values.
|
|
|
|
Any limits passed in here are applied relative to the existing
|
|
constraints. So low is added to the current low value and both will be
|
|
clamped to any existing high value.
|
|
"""
|
|
if high:
|
|
if self.high_mark:
|
|
self.high_mark = min(self.high_mark, self.low_mark + high)
|
|
else:
|
|
self.high_mark = self.low_mark + high
|
|
if low:
|
|
if self.high_mark:
|
|
self.low_mark = min(self.high_mark, self.low_mark + low)
|
|
else:
|
|
self.low_mark = self.low_mark + low
|
|
|
|
def clear_limits(self):
|
|
"""
|
|
Clears any existing limits.
|
|
"""
|
|
self.low_mark, self.high_mark = 0, None
|
|
|
|
def can_filter(self):
|
|
"""
|
|
Returns True if adding filters to this instance is still possible.
|
|
|
|
Typically, this means no limits or offsets have been put on the results.
|
|
"""
|
|
return not (self.low_mark or self.high_mark)
|
|
|
|
def add_fields(self, field_names, allow_m2m=True):
|
|
"""
|
|
Adds the given (model) fields to the select set. The field names are
|
|
added in the order specified.
|
|
"""
|
|
alias = self.get_initial_alias()
|
|
opts = self.get_meta()
|
|
try:
|
|
for name in field_names:
|
|
field, target, u2, joins, u3 = self.setup_joins(
|
|
name.split(LOOKUP_SEP), opts, alias, False, allow_m2m,
|
|
True)
|
|
final_alias = joins[-1]
|
|
col = target.column
|
|
if len(joins) > 1:
|
|
join = self.alias_map[final_alias]
|
|
if col == join[RHS_JOIN_COL]:
|
|
self.unref_alias(final_alias)
|
|
final_alias = join[LHS_ALIAS]
|
|
col = join[LHS_JOIN_COL]
|
|
joins = joins[:-1]
|
|
for join in joins[1:]:
|
|
# Only nullable aliases are promoted, so we don't end up
|
|
# doing unnecessary left outer joins here.
|
|
self.promote_alias(join)
|
|
self.select.append((final_alias, col))
|
|
self.select_fields.append(field)
|
|
except MultiJoin:
|
|
raise FieldError("Invalid field name: '%s'" % name)
|
|
except FieldError:
|
|
names = opts.get_all_field_names() + self.extra_select.keys()
|
|
names.sort()
|
|
raise FieldError("Cannot resolve keyword %r into field. "
|
|
"Choices are: %s" % (name, ", ".join(names)))
|
|
|
|
def add_ordering(self, *ordering):
|
|
"""
|
|
Adds items from the 'ordering' sequence to the query's "order by"
|
|
clause. These items are either field names (not column names) --
|
|
possibly with a direction prefix ('-' or '?') -- or ordinals,
|
|
corresponding to column positions in the 'select' list.
|
|
|
|
If 'ordering' is empty, all ordering is cleared from the query.
|
|
"""
|
|
errors = []
|
|
for item in ordering:
|
|
if not ORDER_PATTERN.match(item):
|
|
errors.append(item)
|
|
if errors:
|
|
raise FieldError('Invalid order_by arguments: %s' % errors)
|
|
if ordering:
|
|
self.order_by.extend(ordering)
|
|
else:
|
|
self.default_ordering = False
|
|
|
|
def clear_ordering(self, force_empty=False):
|
|
"""
|
|
Removes any ordering settings. If 'force_empty' is True, there will be
|
|
no ordering in the resulting query (not even the model's default).
|
|
"""
|
|
self.order_by = []
|
|
self.extra_order_by = ()
|
|
if force_empty:
|
|
self.default_ordering = False
|
|
|
|
def add_count_column(self):
|
|
"""
|
|
Converts the query to do count(...) or count(distinct(pk)) in order to
|
|
get its size.
|
|
"""
|
|
# TODO: When group_by support is added, this needs to be adjusted so
|
|
# that it doesn't totally overwrite the select list.
|
|
if not self.distinct:
|
|
if not self.select:
|
|
select = Count()
|
|
else:
|
|
assert len(self.select) == 1, \
|
|
"Cannot add count col with multiple cols in 'select': %r" % self.select
|
|
select = Count(self.select[0])
|
|
else:
|
|
opts = self.model._meta
|
|
if not self.select:
|
|
select = Count((self.join((None, opts.db_table, None, None)),
|
|
opts.pk.column), True)
|
|
else:
|
|
# Because of SQL portability issues, multi-column, distinct
|
|
# counts need a sub-query -- see get_count() for details.
|
|
assert len(self.select) == 1, \
|
|
"Cannot add count col with multiple cols in 'select'."
|
|
select = Count(self.select[0], True)
|
|
|
|
# Distinct handling is done in Count(), so don't do it at this
|
|
# level.
|
|
self.distinct = False
|
|
self.select = [select]
|
|
self.select_fields = [None]
|
|
self.extra_select = {}
|
|
self.extra_select_params = ()
|
|
|
|
def add_select_related(self, fields):
|
|
"""
|
|
Sets up the select_related data structure so that we only select
|
|
certain related models (as opposed to all models, when
|
|
self.select_related=True).
|
|
"""
|
|
field_dict = {}
|
|
for field in fields:
|
|
d = field_dict
|
|
for part in field.split(LOOKUP_SEP):
|
|
d = d.setdefault(part, {})
|
|
self.select_related = field_dict
|
|
self.related_select_cols = []
|
|
self.related_select_fields = []
|
|
|
|
def add_extra(self, select, select_params, where, params, tables, order_by):
|
|
"""
|
|
Adds data to the various extra_* attributes for user-created additions
|
|
to the query.
|
|
"""
|
|
if select:
|
|
# The extra select might be ordered (because it will be accepting
|
|
# parameters).
|
|
if (isinstance(select, SortedDict) and
|
|
not isinstance(self.extra_select, SortedDict)):
|
|
self.extra_select = SortedDict(self.extra_select)
|
|
self.extra_select.update(select)
|
|
if select_params:
|
|
self.extra_select_params += tuple(select_params)
|
|
if where:
|
|
self.extra_where += tuple(where)
|
|
if params:
|
|
self.extra_params += tuple(params)
|
|
if tables:
|
|
self.extra_tables += tuple(tables)
|
|
if order_by:
|
|
self.extra_order_by = order_by
|
|
|
|
def trim_extra_select(self, names):
|
|
"""
|
|
Removes any aliases in the extra_select dictionary that aren't in
|
|
'names'.
|
|
|
|
This is needed if we are selecting certain values that don't incldue
|
|
all of the extra_select names.
|
|
"""
|
|
for key in set(self.extra_select).difference(set(names)):
|
|
del self.extra_select[key]
|
|
|
|
def set_start(self, start):
|
|
"""
|
|
Sets the table from which to start joining. The start position is
|
|
specified by the related attribute from the base model. This will
|
|
automatically set to the select column to be the column linked from the
|
|
previous table.
|
|
|
|
This method is primarily for internal use and the error checking isn't
|
|
as friendly as add_filter(). Mostly useful for querying directly
|
|
against the join table of many-to-many relation in a subquery.
|
|
"""
|
|
opts = self.model._meta
|
|
alias = self.get_initial_alias()
|
|
field, col, opts, joins, last = self.setup_joins(
|
|
start.split(LOOKUP_SEP), opts, alias, False)
|
|
alias = joins[last[-1]]
|
|
self.select = [(alias, self.alias_map[alias][RHS_JOIN_COL])]
|
|
self.select_fields = [field]
|
|
self.start_meta = opts
|
|
|
|
# The call to setup_joins add an extra reference to everything in
|
|
# joins. So we need to unref everything once, and everything prior to
|
|
# the final join a second time.
|
|
for alias in joins:
|
|
self.unref_alias(alias)
|
|
for alias in joins[:last[-1]]:
|
|
self.unref_alias(alias)
|
|
|
|
def execute_sql(self, result_type=MULTI):
|
|
"""
|
|
Run the query against the database and returns the result(s). The
|
|
return value is a single data item if result_type is SINGLE, or an
|
|
iterator over the results if the result_type is MULTI.
|
|
|
|
result_type is either MULTI (use fetchmany() to retrieve all rows),
|
|
SINGLE (only retrieve a single row), or None (no results expected, but
|
|
the cursor is returned, since it's used by subclasses such as
|
|
InsertQuery).
|
|
"""
|
|
try:
|
|
sql, params = self.as_sql()
|
|
if not sql:
|
|
raise EmptyResultSet
|
|
except EmptyResultSet:
|
|
if result_type == MULTI:
|
|
return empty_iter()
|
|
else:
|
|
return
|
|
|
|
cursor = self.connection.cursor()
|
|
cursor.execute(sql, params)
|
|
|
|
if not result_type:
|
|
return cursor
|
|
if result_type == SINGLE:
|
|
if self.ordering_aliases:
|
|
return cursor.fetchone()[:-len(results.ordering_aliases)]
|
|
return cursor.fetchone()
|
|
|
|
# The MULTI case.
|
|
if self.ordering_aliases:
|
|
return order_modified_iter(cursor, len(self.ordering_aliases),
|
|
self.connection.features.empty_fetchmany_value)
|
|
return iter((lambda: cursor.fetchmany(GET_ITERATOR_CHUNK_SIZE)),
|
|
self.connection.features.empty_fetchmany_value)
|
|
|
|
# Use the backend's custom Query class if it defines one. Otherwise, use the
|
|
# default.
|
|
if connection.features.uses_custom_query_class:
|
|
Query = connection.ops.query_class(Query)
|
|
|
|
def get_order_dir(field, default='ASC'):
|
|
"""
|
|
Returns the field name and direction for an order specification. For
|
|
example, '-foo' is returned as ('foo', 'DESC').
|
|
|
|
The 'default' param is used to indicate which way no prefix (or a '+'
|
|
prefix) should sort. The '-' prefix always sorts the opposite way.
|
|
"""
|
|
dirn = ORDER_DIR[default]
|
|
if field[0] == '-':
|
|
return field[1:], dirn[1]
|
|
return field, dirn[0]
|
|
|
|
def empty_iter():
|
|
"""
|
|
Returns an iterator containing no results.
|
|
"""
|
|
yield iter([]).next()
|
|
|
|
def order_modified_iter(cursor, trim, sentinel):
|
|
"""
|
|
Yields blocks of rows from a cursor. We use this iterator in the special
|
|
case when extra output columns have been added to support ordering
|
|
requirements. We must trim those extra columns before anything else can use
|
|
the results, since they're only needed to make the SQL valid.
|
|
"""
|
|
for rows in iter((lambda: cursor.fetchmany(GET_ITERATOR_CHUNK_SIZE)),
|
|
sentinel):
|
|
yield [r[:-trim] for r in rows]
|
|
|
|
def setup_join_cache(sender):
|
|
"""
|
|
The information needed to join between model fields is something that is
|
|
invariant over the life of the model, so we cache it in the model's Options
|
|
class, rather than recomputing it all the time.
|
|
|
|
This method initialises the (empty) cache when the model is created.
|
|
"""
|
|
sender._meta._join_cache = {}
|
|
|
|
dispatcher.connect(setup_join_cache, signal=signals.class_prepared)
|
|
|