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411 lines
16 KiB
411 lines
16 KiB
""" |
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Query subclasses which provide extra functionality beyond simple data retrieval. |
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""" |
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|
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from django.core.exceptions import FieldError |
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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.query import Query |
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from django.db.models.sql.where import AND |
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|
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__all__ = ['DeleteQuery', 'UpdateQuery', 'InsertQuery', 'DateQuery', |
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'CountQuery'] |
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|
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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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def as_sql(self): |
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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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""" |
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assert len(self.tables) == 1, \ |
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"Can only delete from one table at a time." |
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result = ['DELETE FROM %s' % self.quote_name_unless_alias(self.tables[0])] |
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where, params = self.where.as_sql() |
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result.append('WHERE %s' % where) |
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return ' '.join(result), tuple(params) |
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|
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def do_query(self, table, where): |
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self.tables = [table] |
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self.where = where |
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self.execute_sql(None) |
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|
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def delete_batch_related(self, pk_list): |
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""" |
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Set up and execute delete queries for all the objects related to the |
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primary key values in pk_list. To delete the objects themselves, use |
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the delete_batch() method. |
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|
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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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from django.contrib.contenttypes import generic |
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cls = self.model |
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for related in cls._meta.get_all_related_many_to_many_objects(): |
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if not isinstance(related.field, generic.GenericRelation): |
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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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where.add((None, related.field.m2m_reverse_name(), |
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related.field, 'in', |
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pk_list[offset : offset+GET_ITERATOR_CHUNK_SIZE]), |
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AND) |
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self.do_query(related.field.m2m_db_table(), where) |
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|
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for f in cls._meta.many_to_many: |
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w1 = self.where_class() |
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if isinstance(f, generic.GenericRelation): |
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from django.contrib.contenttypes.models import ContentType |
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field = f.rel.to._meta.get_field(f.content_type_field_name) |
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w1.add((None, field.column, field, 'exact', |
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ContentType.objects.get_for_model(cls).id), AND) |
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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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where.add((None, f.m2m_column_name(), f, 'in', |
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pk_list[offset : offset + GET_ITERATOR_CHUNK_SIZE]), |
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AND) |
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if w1: |
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where.add(w1, AND) |
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self.do_query(f.m2m_db_table(), where) |
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|
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def delete_batch(self, pk_list): |
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""" |
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Set up and execute delete queries for all the objects in pk_list. This |
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should be called after delete_batch_related(), if necessary. |
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|
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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((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) |
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|
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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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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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|
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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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|
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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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|
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def execute_sql(self, result_type=None): |
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""" |
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Execute the specified update. Returns the number of rows affected by |
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the primary update query (there could be other updates on related |
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tables, but their rowcounts are not returned). |
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""" |
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cursor = super(UpdateQuery, self).execute_sql(result_type) |
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rows = cursor.rowcount |
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del cursor |
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for query in self.get_related_updates(): |
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query.execute_sql(result_type) |
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return rows |
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|
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def as_sql(self): |
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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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""" |
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self.pre_sql_setup() |
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if not self.values: |
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return '', () |
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table = self.tables[0] |
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qn = self.quote_name_unless_alias |
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result = ['UPDATE %s' % qn(table)] |
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result.append('SET') |
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values, update_params = [], [] |
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for name, val, placeholder in self.values: |
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if val is not None: |
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values.append('%s = %s' % (qn(name), placeholder)) |
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update_params.append(val) |
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else: |
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values.append('%s = NULL' % qn(name)) |
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result.append(', '.join(values)) |
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where, params = self.where.as_sql() |
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if where: |
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result.append('WHERE %s' % where) |
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return ' '.join(result), tuple(update_params + params) |
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def pre_sql_setup(self): |
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""" |
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If the update depends on results from other tables, we need to do some |
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munging of the "where" conditions to match the format required for |
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(portable) SQL updates. That is done here. |
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Further, if we are going to be running multiple updates, we pull out |
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the id values to update at this point so that they don't change as a |
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result of the progressive updates. |
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""" |
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self.select_related = False |
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self.clear_ordering(True) |
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super(UpdateQuery, self).pre_sql_setup() |
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count = self.count_active_tables() |
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if not self.related_updates and count == 1: |
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return |
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# We need to use a sub-select in the where clause to filter on things |
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# from other tables. |
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query = self.clone(klass=Query) |
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query.bump_prefix() |
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query.extra_select = {} |
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first_table = query.tables[0] |
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if query.alias_refcount[first_table] == 1: |
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# We can remove one table from the inner query. |
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query.unref_alias(first_table) |
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for i in xrange(1, len(query.tables)): |
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table = query.tables[i] |
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if query.alias_refcount[table]: |
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break |
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join_info = query.alias_map[table] |
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query.select = [(join_info[RHS_ALIAS], join_info[RHS_JOIN_COL])] |
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must_pre_select = False |
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else: |
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query.select = [] |
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query.add_fields([query.model._meta.pk.name]) |
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must_pre_select = not self.connection.features.update_can_self_select |
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# Now we adjust the current query: reset the where clause and get rid |
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# of all the tables we don't need (since they're in the sub-select). |
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self.where = self.where_class() |
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if self.related_updates or must_pre_select: |
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# Either we're using the idents in multiple update queries (so |
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# don't want them to change), or the db backend doesn't support |
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# selecting from the updating table (e.g. MySQL). |
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idents = [] |
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for rows in query.execute_sql(MULTI): |
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idents.extend([r[0] for r in rows]) |
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self.add_filter(('pk__in', idents)) |
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self.related_ids = idents |
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else: |
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# The fast path. Filters and updates in one query. |
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self.add_filter(('pk__in', query)) |
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for alias in self.tables[1:]: |
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self.alias_refcount[alias] = 0 |
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def clear_related(self, related_field, pk_list): |
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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((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.column, None, '%s')] |
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self.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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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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from django.db.models.base import Model |
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for field, model, val in values_seq: |
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# FIXME: Some sort of db_prep_* is probably more appropriate here. |
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if field.rel and isinstance(val, Model): |
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val = val.pk |
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# Getting the placeholder for the field. |
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if hasattr(field, 'get_placeholder'): |
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placeholder = field.get_placeholder(val) |
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else: |
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placeholder = '%s' |
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if model: |
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self.add_related_update(model, field.column, val, placeholder) |
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else: |
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self.values.append((field.column, val, placeholder)) |
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def add_related_update(self, model, column, value, placeholder): |
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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((column, value, placeholder)) |
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except KeyError: |
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self.related_updates[model] = [(column, value, placeholder)] |
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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, self.connection) |
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query.values = values |
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if self.related_ids: |
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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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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 = {'columns': self.columns[:], 'values': self.values[:], |
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'params': self.params} |
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return super(InsertQuery, self).clone(klass, extras) |
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def as_sql(self): |
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# We don't need quote_name_unless_alias() here, since these are all |
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# going to be column names (so we can avoid the extra overhead). |
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qn = self.connection.ops.quote_name |
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result = ['INSERT INTO %s' % qn(self.model._meta.db_table)] |
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result.append('(%s)' % ', '.join([qn(c) for c in self.columns])) |
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result.append('VALUES (%s)' % ', '.join(self.values)) |
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return ' '.join(result), self.params |
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def execute_sql(self, return_id=False): |
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cursor = super(InsertQuery, self).execute_sql(None) |
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if return_id: |
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return self.connection.ops.last_insert_id(cursor, |
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self.model._meta.db_table, self.model._meta.pk.column) |
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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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if hasattr(field, 'get_placeholder'): |
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# Some fields (e.g. geo fields) need special munging before |
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# they can be inserted. |
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placeholders.append(field.get_placeholder(val)) |
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else: |
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placeholders.append('%s') |
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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(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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def __getstate__(self): |
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""" |
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Special DateQuery-specific pickle handling. |
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""" |
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for elt in self.select: |
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if isinstance(elt, Date): |
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# Eliminate a method reference that can't be pickled. The |
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# __setstate__ method restores this. |
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elt.date_sql_func = None |
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return super(DateQuery, self).__getstate__() |
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|
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def __setstate__(self, obj_dict): |
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super(DateQuery, self).__setstate__(obj_dict) |
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for elt in self.select: |
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if isinstance(elt, Date): |
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self.date_sql_func = self.connection.ops.date_trunc_sql |
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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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from django.db.models.fields import DateTimeField |
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fields = [DateTimeField()] |
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else: |
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from django.db.backends.util import typecast_timestamp |
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needs_string_cast = self.connection.features.needs_datetime_string_cast |
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offset = len(self.extra_select) |
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for rows in self.execute_sql(MULTI): |
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for row in rows: |
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date = row[offset] |
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if resolve_columns: |
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date = self.resolve_columns(row, fields)[offset] |
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elif needs_string_cast: |
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date = typecast_timestamp(str(date)) |
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yield date |
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def add_date_select(self, field, 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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result = self.setup_joins([field.name], self.get_meta(), |
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self.get_initial_alias(), False) |
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alias = result[3][-1] |
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select = Date((alias, field.column), lookup_type, |
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self.connection.ops.date_trunc_sql) |
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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.distinct = True |
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self.order_by = order == 'ASC' and [1] or [-1] |
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|
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class CountQuery(Query): |
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""" |
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A CountQuery knows how to take a normal query which would select over |
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multiple distinct columns and turn it into SQL that can be used on a |
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variety of backends (it requires a select in the FROM clause). |
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""" |
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def get_from_clause(self): |
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result, params = self._query.as_sql() |
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return ['(%s) A1' % result], params |
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|
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def get_ordering(self): |
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return ()
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