Commit 4276b519 authored by Alex Gaynor's avatar Alex Gaynor
Browse files

Fixed #12687 -- fixed an issue with aggregates and counts in conjunction with... 

Fixed #12687 -- fixed an issue with aggregates and counts in conjunction with annotations where the QuerySet was provably empty.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@14586 bcc190cf-cafb-0310-a4f2-bffc1f526a37
parent 3e9d2f81

django/db/models/sql/aggregates.py

+1 −0
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ class AggregateField(object): 
    """

    def __init__(self, internal_type):

        self.internal_type = internal_type



    def get_internal_type(self):

        return self.internal_type

django/db/models/sql/query.py

+16 −4
Original line number Diff line number Diff line
@@ -337,7 +337,7 @@ class Query(object): 
        # information but retrieves only the first row. Aggregate

        # over the subquery instead.

        if self.group_by is not None:

            from subqueries import AggregateQuery

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

            query = AggregateQuery(self.model)



            obj = self.clone()
@@ -349,7 +349,13 @@ class Query(object): 
                    query.aggregate_select[alias] = aggregate

                    del obj.aggregate_select[alias]



            try:

                query.add_subquery(obj, using)

            except EmptyResultSet:

                return dict(

                    (alias, None)

                    for alias in query.aggregate_select

                )

        else:

            query = self

            self.select = []
@@ -382,13 +388,19 @@ class Query(object): 
            # If a select clause exists, then the query has already started to

            # specify the columns that are to be returned.

            # In this case, we need to use a subquery to evaluate the count.

            from subqueries import AggregateQuery

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

            subquery = obj

            subquery.clear_ordering(True)

            subquery.clear_limits()



            obj = AggregateQuery(obj.model)

            try:

                obj.add_subquery(subquery, using=using)

            except EmptyResultSet:

                # add_subquery evaluates the query, if it's an EmptyResultSet

                # then there are can be no results, and therefore there the

                # count is obviously 0

                return 0



        obj.add_count_column()

        number = obj.get_aggregation(using=using)[None]

django/db/models/sql/subqueries.py

+1 −0
Original line number Diff line number Diff line
@@ -11,6 +11,7 @@ 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']

tests/regressiontests/aggregation_regress/tests.py

+18 −0
Original line number Diff line number Diff line
@@ -622,6 +622,24 @@ class AggregationTests(TestCase): 
            lambda: Book.objects.annotate(mean_age=Avg('authors__age')).annotate(Avg('mean_age'))

        )



    def test_empty_filter_count(self):

        self.assertEqual(

            Author.objects.filter(id__in=[]).annotate(Count("friends")).count(),

            0

        )



    def test_empty_filter_aggregate(self):

        self.assertEqual(

            Author.objects.filter(id__in=[]).annotate(Count("friends")).aggregate(Count("pk")),

            {"pk__count": None}

        )



    def test_annotate_and_join(self):

        self.assertEqual(

            Author.objects.annotate(c=Count("friends__name")).exclude(friends__name="Joe").count(),

            Author.objects.count()

        )



    @skipUnlessDBFeature('supports_stddev')

    def test_stddev(self):

        self.assertEqual(