Fixed #27849 -- Added filtering support to aggregates.

2 files changed, 8 insertions, 0 deletions

diff --git a/django/db/backends/base/features.py b/django/db/backends/base/features.py
index 7626595741..22c2990e77 100644
--- a/django/db/backends/base/features.py
+++ b/django/db/backends/base/features.py
@@ -229,6 +229,10 @@ class BaseDatabaseFeatures:
     supports_select_difference = True
     supports_slicing_ordering_in_compound = False
 
+    # Does the database support SQL 2003 FILTER (WHERE ...) in aggregate
+    # expressions?
+    supports_aggregate_filter_clause = False
+
     # Does the backend support indexing a TextField?
     supports_index_on_text_field = True
 
diff --git a/django/db/backends/postgresql/features.py b/django/db/backends/postgresql/features.py
index 647fb9dc7f..3c7a7af80f 100644
--- a/django/db/backends/postgresql/features.py
+++ b/django/db/backends/postgresql/features.py
@@ -51,6 +51,10 @@ class DatabaseFeatures(BaseDatabaseFeatures):
     $$ LANGUAGE plpgsql;"""
 
     @cached_property
+    def supports_aggregate_filter_clause(self):
+        return self.connection.pg_version >= 90400
+
+    @cached_property
     def has_select_for_update_skip_locked(self):
         return self.connection.pg_version >= 90500