"""
Query subclasses which provide extra functionality beyond simple data retrieval.
"""
from django.core.exceptions import FieldError
from django.db import connections
from django.db.models.sql.constants import *
from django.db.models.sql.datastructures import Date
from django.db.models.sql.expressions import SQLEvaluator
from django.db.models.sql.query import Query
from django.db.models.sql.where import AND,Constraint
__all__ = ['DeleteQuery', 'UpdateQuery', 'InsertQuery', 'DateQuery',
'AggregateQuery']
class DeleteQuery(Query):
"""
Delete queries are done through this class, since they are more constrained
than general queries.
"""
compiler = 'SQLDeleteCompiler'
def do_query(self, table, where, using):
self.tables = [table]
self.where = where
self.get_compiler(using).execute_sql(None)
def delete_batch(self, pk_list, using):
"""
Set up and execute delete queries for all the objects in pk_list.
More than one physical query may be executed if there are a
lot of values in pk_list.
"""
for offset in range(0, len(pk_list), GET_ITERATOR_CHUNK_SIZE):
where = self.where_class()
field = self.model._meta.pk
where.add((Constraint(None, field.column, field), 'in',
pk_list[offset : offset + GET_ITERATOR_CHUNK_SIZE]), AND)
self.do_query(self.model._meta.db_table, where, using=using)
class UpdateQuery(Query):
"""
Represents an "update" SQL query.
"""
compiler = 'SQLUpdateCompiler'
def __init__(self, *args, **kwargs):
super(UpdateQuery, self).__init__(*args, **kwargs)
self._setup_query()
def _setup_query(self):
"""
Runs on initialization and after cloning. Any attributes that would
normally be set in __init__ should go in here, instead, so that they
are also set up after a clone() call.
"""
self.values = []
self.related_ids = None
if not hasattr(self, 'related_updates'):
self.related_updates = {}
def clone(self, klass=None, **kwargs):
return super(UpdateQuery, self).clone(klass,
related_updates=self.related_updates.copy(), **kwargs)
def clear_related(self, related_field, pk_list, using):
"""
Set up and execute an update query that clears related entries for the
keys in pk_list.
This is used by the QuerySet.delete_objects() method.
"""
for offset in range(0, len(pk_list), GET_ITERATOR_CHUNK_SIZE):
self.where = self.where_class()
f = self.model._meta.pk
self.where.add((Constraint(None, f.column, f), 'in',
pk_list[offset : offset + GET_ITERATOR_CHUNK_SIZE]),
AND)
self.values = [(related_field, None, None)]
self.get_compiler(using).execute_sql(None)
def add_update_values(self, values):
"""
Convert a dictionary of field name to value mappings into an update
query. This is the entry point for the public update() method on
querysets.
"""
values_seq = []
for name, val in values.iteritems():
field, model, direct, m2m = self.model._meta.get_field_by_name(name)
if not direct or m2m:
raise FieldError('Cannot update model field %r (only non-relations and foreign keys permitted).' % field)
if model:
self.add_related_update(model, field, val)
continue
values_seq.append((field, model, val))
return self.add_update_fields(values_seq)
def add_update_fields(self, values_seq):
"""
Turn a sequence of (field, model, value) triples into an update query.
Used by add_update_values() as well as the "fast" update path when
saving models.
"""
self.values.extend(values_seq)
def add_related_update(self, model, field, value):
"""
Adds (name, value) to an update query for an ancestor model.
Updates are coalesced so that we only run one update query per ancestor.
"""
try:
self.related_updates[model].append((field, None, value))
except KeyError:
self.related_updates[model] = [(field, None, value)]
def get_related_updates(self):
"""
Returns a list of query objects: one for each update required to an
ancestor model. Each query will have the same filtering conditions as
the current query but will only update a single table.
"""
if not self.related_updates:
return []
result = []
for model, values in self.related_updates.iteritems():
query = UpdateQuery(model)
query.values = values
if self.related_ids is not None:
query.add_filter(('pk__in', self.related_ids))
result.append(query)
return result
class InsertQuery(Query):
compiler = 'SQLInsertCompiler'
def __init__(self, *args, **kwargs):
super(InsertQuery, self).__init__(*args, **kwargs)
self.columns = []
self.values = []
self.params = ()
def clone(self, klass=None, **kwargs):
extras = {
'columns': self.columns[:],
'values': self.values[:],
'params': self.params
}
extras.update(kwargs)
return super(InsertQuery, self).clone(klass, **extras)
def insert_values(self, insert_values, raw_values=False):
"""
Set up the insert query from the 'insert_values' dictionary. The
dictionary gives the model field names and their target values.
If 'raw_values' is True, the values in the 'insert_values' dictionary
are inserted directly into the query, rather than passed as SQL
parameters. This provides a way to insert NULL and DEFAULT keywords
into the query, for example.
"""
placeholders, values = [], []
for field, val in insert_values:
placeholders.append((field, val))
self.columns.append(field.column)
values.append(val)
if raw_values:
self.values.extend([(None, v) for v in values])
else:
self.params += tuple(values)
self.values.extend(placeholders)
class DateQuery(Query):
"""
A DateQuery is a normal query, except that it specifically selects a single
date field. This requires some special handling when converting the results
back to Python objects, so we put it in a separate class.
"""
compiler = 'SQLDateCompiler'
def add_date_select(self, field, lookup_type, order='ASC'):
"""
Converts the query into a date extraction query.
"""
result = self.setup_joins([field.name], self.get_meta(),
self.get_initial_alias(), False)
alias = result[3][-1]
select = Date((alias, field.column), lookup_type)
self.select = [select]
self.select_fields = [None]
self.select_related = False # See #7097.
self.set_extra_mask([])
self.distinct = True
self.order_by = order == 'ASC' and [1] or [-1]
class AggregateQuery(Query):
"""
An AggregateQuery takes another query as a parameter to the FROM
clause and only selects the elements in the provided list.
"""
compiler = 'SQLAggregateCompiler'
def add_subquery(self, query, using):
self.subquery, self.sub_params = query.get_compiler(using).as_sql(with_col_aliases=True)
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