228 lines
8.0 KiB
Python
228 lines
8.0 KiB
Python
"""
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Query subclasses which provide extra functionality beyond simple data retrieval.
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"""
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from django.core.exceptions import FieldError
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from django.db import connections
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from django.db.models.fields import DateField, FieldDoesNotExist
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from django.db.models.sql.constants import *
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from django.db.models.sql.datastructures import Date
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from django.db.models.sql.expressions import SQLEvaluator
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from django.db.models.sql.query import Query
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from django.db.models.sql.where import AND, Constraint
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__all__ = ['DeleteQuery', 'UpdateQuery', 'InsertQuery', 'DateQuery',
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'AggregateQuery']
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class DeleteQuery(Query):
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"""
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Delete queries are done through this class, since they are more constrained
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than general queries.
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"""
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compiler = 'SQLDeleteCompiler'
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def do_query(self, table, where, using):
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self.tables = [table]
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self.where = where
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self.get_compiler(using).execute_sql(None)
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def delete_batch(self, pk_list, using):
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"""
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Set up and execute delete queries for all the objects in pk_list.
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More than one physical query may be executed if there are a
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lot of values in pk_list.
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"""
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for offset in range(0, len(pk_list), GET_ITERATOR_CHUNK_SIZE):
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where = self.where_class()
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field = self.model._meta.pk
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where.add((Constraint(None, field.column, field), 'in',
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pk_list[offset : offset + GET_ITERATOR_CHUNK_SIZE]), AND)
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self.do_query(self.model._meta.db_table, where, using=using)
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class UpdateQuery(Query):
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"""
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Represents an "update" SQL query.
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"""
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compiler = 'SQLUpdateCompiler'
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def __init__(self, *args, **kwargs):
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super(UpdateQuery, self).__init__(*args, **kwargs)
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self._setup_query()
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def _setup_query(self):
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"""
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Runs on initialization and after cloning. Any attributes that would
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normally be set in __init__ should go in here, instead, so that they
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are also set up after a clone() call.
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"""
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self.values = []
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self.related_ids = None
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if not hasattr(self, 'related_updates'):
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self.related_updates = {}
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def clone(self, klass=None, **kwargs):
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return super(UpdateQuery, self).clone(klass,
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related_updates=self.related_updates.copy(), **kwargs)
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def clear_related(self, related_field, pk_list, using):
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"""
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Set up and execute an update query that clears related entries for the
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keys in pk_list.
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This is used by the QuerySet.delete_objects() method.
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"""
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for offset in range(0, len(pk_list), GET_ITERATOR_CHUNK_SIZE):
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self.where = self.where_class()
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f = self.model._meta.pk
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self.where.add((Constraint(None, f.column, f), 'in',
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pk_list[offset : offset + GET_ITERATOR_CHUNK_SIZE]),
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AND)
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self.values = [(related_field, None, None)]
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self.get_compiler(using).execute_sql(None)
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def add_update_values(self, values):
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"""
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Convert a dictionary of field name to value mappings into an update
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query. This is the entry point for the public update() method on
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querysets.
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"""
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values_seq = []
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for name, val in values.iteritems():
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field, model, direct, m2m = self.model._meta.get_field_by_name(name)
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if not direct or m2m:
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raise FieldError('Cannot update model field %r (only non-relations and foreign keys permitted).' % field)
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if model:
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self.add_related_update(model, field, val)
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continue
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values_seq.append((field, model, val))
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return self.add_update_fields(values_seq)
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def add_update_fields(self, values_seq):
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"""
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Turn a sequence of (field, model, value) triples into an update query.
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Used by add_update_values() as well as the "fast" update path when
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saving models.
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"""
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self.values.extend(values_seq)
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def add_related_update(self, model, field, value):
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"""
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Adds (name, value) to an update query for an ancestor model.
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Updates are coalesced so that we only run one update query per ancestor.
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"""
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try:
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self.related_updates[model].append((field, None, value))
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except KeyError:
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self.related_updates[model] = [(field, None, value)]
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def get_related_updates(self):
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"""
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Returns a list of query objects: one for each update required to an
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ancestor model. Each query will have the same filtering conditions as
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the current query but will only update a single table.
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"""
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if not self.related_updates:
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return []
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result = []
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for model, values in self.related_updates.iteritems():
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query = UpdateQuery(model)
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query.values = values
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if self.related_ids is not None:
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query.add_filter(('pk__in', self.related_ids))
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result.append(query)
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return result
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class InsertQuery(Query):
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compiler = 'SQLInsertCompiler'
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def __init__(self, *args, **kwargs):
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super(InsertQuery, self).__init__(*args, **kwargs)
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self.columns = []
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self.values = []
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self.params = ()
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def clone(self, klass=None, **kwargs):
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extras = {
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'columns': self.columns[:],
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'values': self.values[:],
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'params': self.params
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}
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extras.update(kwargs)
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return super(InsertQuery, self).clone(klass, **extras)
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def insert_values(self, insert_values, raw_values=False):
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"""
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Set up the insert query from the 'insert_values' dictionary. The
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dictionary gives the model field names and their target values.
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If 'raw_values' is True, the values in the 'insert_values' dictionary
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are inserted directly into the query, rather than passed as SQL
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parameters. This provides a way to insert NULL and DEFAULT keywords
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into the query, for example.
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"""
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placeholders, values = [], []
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for field, val in insert_values:
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placeholders.append((field, val))
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self.columns.append(field.column)
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values.append(val)
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if raw_values:
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self.values.extend([(None, v) for v in values])
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else:
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self.params += tuple(values)
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self.values.extend(placeholders)
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class DateQuery(Query):
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"""
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A DateQuery is a normal query, except that it specifically selects a single
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date field. This requires some special handling when converting the results
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back to Python objects, so we put it in a separate class.
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"""
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compiler = 'SQLDateCompiler'
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def add_date_select(self, field_name, lookup_type, order='ASC'):
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"""
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Converts the query into a date extraction query.
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"""
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try:
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result = self.setup_joins(
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field_name.split(LOOKUP_SEP),
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self.get_meta(),
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self.get_initial_alias(),
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False
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)
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except FieldError:
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raise FieldDoesNotExist("%s has no field named '%s'" % (
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self.model._meta.object_name, field_name
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))
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field = result[0]
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assert isinstance(field, DateField), "%r isn't a DateField." \
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% field.name
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alias = result[3][-1]
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select = Date((alias, field.column), lookup_type)
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self.select = [select]
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self.select_fields = [None]
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self.select_related = False # See #7097.
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self.set_extra_mask([])
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self.distinct = True
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self.order_by = order == 'ASC' and [1] or [-1]
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if field.null:
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self.add_filter(("%s__isnull" % field_name, False))
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class AggregateQuery(Query):
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"""
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An AggregateQuery takes another query as a parameter to the FROM
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clause and only selects the elements in the provided list.
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"""
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compiler = 'SQLAggregateCompiler'
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def add_subquery(self, query, using):
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self.subquery, self.sub_params = query.get_compiler(using).as_sql(with_col_aliases=True)
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