""" 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)