Commit 7737305a authored by Anssi Kääriäinen's avatar Anssi Kääriäinen
Browse files

Fixed #12886 -- aggregation over sliced queryset

parent 7d28bed1

django/db/models/query.py

+2 −3
Original line number Diff line number Diff line
@@ -313,14 +313,13 @@ class QuerySet(object): 
            kwargs[arg.default_alias] = arg



        query = self.query.clone()



        force_subq = query.low_mark != 0 or query.high_mark is not None

        aggregate_names = []

        for (alias, aggregate_expr) in kwargs.items():

            query.add_aggregate(aggregate_expr, self.model, alias,

                                is_summary=True)

            aggregate_names.append(alias)



        return query.get_aggregation(using=self.db)

        return query.get_aggregation(using=self.db, force_subq=force_subq)



    def count(self):

        """

django/db/models/sql/query.py

+4 −4
Original line number Diff line number Diff line
@@ -315,7 +315,7 @@ class Query(object): 
            # Return value depends on the type of the field being processed.

            return self.convert_values(value, aggregate.field, connection)



    def get_aggregation(self, using):

    def get_aggregation(self, using, force_subq=False):

        """

        Returns the dictionary with the values of the existing aggregations.

        """
@@ -325,18 +325,18 @@ class Query(object): 
        # If there is a group by clause, aggregating does not add useful

        # information but retrieves only the first row. Aggregate

        # over the subquery instead.

        if self.group_by is not None:

        if self.group_by is not None or force_subq:



            from django.db.models.sql.subqueries import AggregateQuery

            query = AggregateQuery(self.model)



            obj = self.clone()

            relabels = dict((t, 'subquery') for t in self.tables)



            # Remove any aggregates marked for reduction from the subquery

            # and move them to the outer AggregateQuery.

            for alias, aggregate in self.aggregate_select.items():

                if aggregate.is_summary:

                    query.aggregate_select[alias] = aggregate

                    query.aggregate_select[alias] = aggregate.relabeled_clone(relabels)

                    del obj.aggregate_select[alias]



            try:

tests/aggregation/tests.py

+8 −0
Original line number Diff line number Diff line
@@ -617,3 +617,11 @@ class BaseAggregateTestCase(TestCase): 
        # Check internal state

        self.assertIsNone(annotated_books.query.alias_map["aggregation_book"].join_type)

        self.assertIsNone(excluded_books.query.alias_map["aggregation_book"].join_type)



    def test_ticket12886(self):

        """

        Check that aggregation over sliced queryset works correctly.

        """

        qs = Book.objects.all().order_by('-rating')[0:3]

        vals = qs.aggregate(average_top3_rating=Avg('rating'))['average_top3_rating']

        self.assertAlmostEqual(vals, 4.5, places=2)