Fixed #24887 -- Removed one-arg limit from models.aggregate

django/contrib/gis/db/models/aggregates.py

@@ -25,7 +25,8 @@ class GeoAggregate(Aggregate):
 
     def resolve_expression(self, query=None, allow_joins=True, reuse=None, summarize=False, for_save=False):
         c = super(GeoAggregate, self).resolve_expression(query, allow_joins, reuse, summarize, for_save)
-        if not hasattr(c.input_field.field, 'geom_type'):
+        for expr in c.get_source_expressions():
+            if not hasattr(expr.field, 'geom_type'):
                 raise ValueError('Geospatial aggregates only allowed on geometry fields.')
         return c
 

django/db/backends/sqlite3/operations.py

@@ -35,16 +35,18 @@ class DatabaseOperations(BaseDatabaseOperations):
         bad_fields = (fields.DateField, fields.DateTimeField, fields.TimeField)
         bad_aggregates = (aggregates.Sum, aggregates.Avg, aggregates.Variance, aggregates.StdDev)
         if isinstance(expression, bad_aggregates):
+            for expr in expression.get_source_expressions():
                 try:
-                output_field = expression.input_field.output_field
+                    output_field = expr.output_field
                     if isinstance(output_field, bad_fields):
                         raise NotImplementedError(
-                        'You cannot use Sum, Avg, StdDev and Variance aggregations '
-                        'on date/time fields in sqlite3 '
-                        'since date/time is saved as text.')
+                            'You cannot use Sum, Avg, StdDev, and Variance '
+                            'aggregations on date/time fields in sqlite3 '
+                            'since date/time is saved as text.'
+                        )
                 except FieldError:
-                # not every sub-expression has an output_field which is fine to
-                # ignore
+                    # Not every subexpression has an output_field which is fine
+                    # to ignore.
                     pass
 
     def date_extract_sql(self, lookup_type, field_name):

django/db/models/aggregates.py

@@ -15,13 +15,15 @@ class Aggregate(Func):
     name = None
 
     def resolve_expression(self, query=None, allow_joins=True, reuse=None, summarize=False, for_save=False):
-        assert len(self.source_expressions) == 1
         # Aggregates are not allowed in UPDATE queries, so ignore for_save
         c = super(Aggregate, self).resolve_expression(query, allow_joins, reuse, summarize)
-        if c.source_expressions[0].contains_aggregate and not summarize:
-            name = self.source_expressions[0].name
-            raise FieldError("Cannot compute %s('%s'): '%s' is an aggregate" % (
-                c.name, name, name))
+        if not summarize:
+            expressions = c.get_source_expressions()
+            for index, expr in enumerate(expressions):
+                if expr.contains_aggregate:
+                    before_resolved = self.get_source_expressions()[index]
+                    name = before_resolved.name if hasattr(before_resolved, 'name') else repr(before_resolved)
+                    raise FieldError("Cannot compute %s('%s'): '%s' is an aggregate" % (c.name, name, name))
         c._patch_aggregate(query)  # backward-compatibility support
         return c
 
@@ -31,8 +33,9 @@ class Aggregate(Func):
 
     @property
     def default_alias(self):
-        if hasattr(self.source_expressions[0], 'name'):
-            return '%s__%s' % (self.source_expressions[0].name, self.name.lower())
+        expressions = self.get_source_expressions()
+        if len(expressions) == 1 and hasattr(expressions[0], 'name'):
+            return '%s__%s' % (expressions[0].name, self.name.lower())
         raise TypeError("Complex expressions require an alias")
 
     def get_group_by_cols(self):

tests/aggregation/tests.py

@@ -985,9 +985,31 @@ class AggregateTestCase(TestCase):
         self.assertEqual(author.sum_age, other_author.sum_age)
 
     def test_annotated_aggregate_over_annotated_aggregate(self):
-        with six.assertRaisesRegex(self, FieldError, "Cannot compute Sum\('id__max'\): 'id__max' is an aggregate"):
+        with self.assertRaisesMessage(FieldError, "Cannot compute Sum('id__max'): 'id__max' is an aggregate"):
             Book.objects.annotate(Max('id')).annotate(Sum('id__max'))
 
+        class MyMax(Max):
+            def as_sql(self, compiler, connection):
+                self.set_source_expressions(self.get_source_expressions()[0:1])
+                return super(MyMax, self).as_sql(compiler, connection)
+
+        with self.assertRaisesMessage(FieldError, "Cannot compute Max('id__max'): 'id__max' is an aggregate"):
+            Book.objects.annotate(Max('id')).annotate(my_max=MyMax('id__max', 'price'))
+
+    def test_multi_arg_aggregate(self):
+        class MyMax(Max):
+            def as_sql(self, compiler, connection):
+                self.set_source_expressions(self.get_source_expressions()[0:1])
+                return super(MyMax, self).as_sql(compiler, connection)
+
+        with self.assertRaisesMessage(TypeError, 'Complex aggregates require an alias'):
+            Book.objects.aggregate(MyMax('pages', 'price'))
+
+        with self.assertRaisesMessage(TypeError, 'Complex annotations require an alias'):
+            Book.objects.annotate(MyMax('pages', 'price'))
+
+        Book.objects.aggregate(max_field=MyMax('pages', 'price'))
+
     def test_add_implementation(self):
         class MySum(Sum):
             pass