[1.8.x] Fixed #24833 -- Fixed Case expressions with exclude().

4 files changed, 39 insertions, 8 deletions

diff --git a/django/db/models/query_utils.py b/django/db/models/query_utils.py
index eca060e667..16496b7fad 100644
--- a/django/db/models/query_utils.py
+++ b/django/db/models/query_utils.py
@@ -263,3 +263,17 @@ def refs_aggregate(lookup_parts, aggregates):
         if level_n_lookup in aggregates and aggregates[level_n_lookup].contains_aggregate:
             return aggregates[level_n_lookup], lookup_parts[n:]
     return False, ()
+
+
+def refs_expression(lookup_parts, annotations):
+    """
+    A helper method to check if the lookup_parts contains references
+    to the given annotations set. Because the LOOKUP_SEP is contained in the
+    default annotation names we must check each prefix of the lookup_parts
+    for a match.
+    """
+    for n in range(len(lookup_parts) + 1):
+        level_n_lookup = LOOKUP_SEP.join(lookup_parts[0:n])
+        if level_n_lookup in annotations and annotations[level_n_lookup]:
+            return annotations[level_n_lookup], lookup_parts[n:]
+    return False, ()
diff --git a/django/db/models/sql/query.py b/django/db/models/sql/query.py
index 1a86266e6c..d0b56449b2 100644
--- a/django/db/models/sql/query.py
+++ b/django/db/models/sql/query.py
@@ -17,7 +17,9 @@ from django.db import DEFAULT_DB_ALIAS, connections
 from django.db.models.aggregates import Count
 from django.db.models.constants import LOOKUP_SEP
 from django.db.models.expressions import Col, Ref
-from django.db.models.query_utils import Q, PathInfo, refs_aggregate
+from django.db.models.query_utils import (
+    Q, PathInfo, refs_aggregate, refs_expression,
+)
 from django.db.models.sql.constants import (
     INNER, LOUTER, ORDER_DIR, ORDER_PATTERN, QUERY_TERMS, SINGLE,
 )
@@ -1027,9 +1029,9 @@ class Query(object):
         """
         lookup_splitted = lookup.split(LOOKUP_SEP)
         if self._annotations:
-            aggregate, aggregate_lookups = refs_aggregate(lookup_splitted, self.annotations)
-            if aggregate:
-                return aggregate_lookups, (), aggregate
+            expression, expression_lookups = refs_expression(lookup_splitted, self.annotations)
+            if expression:
+                return expression_lookups, (), expression
         _, field, _, lookup_parts = self.names_to_path(lookup_splitted, self.get_meta())
         field_parts = lookup_splitted[0:len(lookup_splitted) - len(lookup_parts)]
         if len(lookup_parts) == 0:
@@ -1144,7 +1146,7 @@ class Query(object):
         arg, value = filter_expr
         if not arg:
             raise FieldError("Cannot parse keyword query %r" % arg)
-        lookups, parts, reffed_aggregate = self.solve_lookup_type(arg)
+        lookups, parts, reffed_expression = self.solve_lookup_type(arg)
         if not allow_joins and len(parts) > 1:
             raise FieldError("Joined field references are not permitted in this query")
 
@@ -1153,12 +1155,12 @@ class Query(object):
         value, lookups, used_joins = self.prepare_lookup_value(value, lookups, can_reuse, allow_joins)
 
         clause = self.where_class()
-        if reffed_aggregate:
-            condition = self.build_lookup(lookups, reffed_aggregate, value)
+        if reffed_expression:
+            condition = self.build_lookup(lookups, reffed_expression, value)
             if not condition:
                 # Backwards compat for custom lookups
                 assert len(lookups) == 1
-                condition = (reffed_aggregate, lookups[0], value)
+                condition = (reffed_expression, lookups[0], value)
             clause.add(condition, AND)
             return clause, []
 
diff --git a/docs/releases/1.8.3.txt b/docs/releases/1.8.3.txt
index 4f98027f7e..d544183445 100644
--- a/docs/releases/1.8.3.txt
+++ b/docs/releases/1.8.3.txt
@@ -50,3 +50,6 @@ Bugfixes
 
 * Fixed recording of applied status for squashed (replacement) migrations
   (:ticket:`24628`).
+
+* Fixed queryset annotations when using ``Case`` expressions with ``exclude()``
+  (:ticket:`24833`).
diff --git a/tests/expressions_case/tests.py b/tests/expressions_case/tests.py
index 58dc7ca80d..8c081dde9a 100644
--- a/tests/expressions_case/tests.py
+++ b/tests/expressions_case/tests.py
@@ -240,6 +240,18 @@ class CaseExpressionTests(TestCase):
             transform=itemgetter('integer', 'max', 'test')
         )
 
+    def test_annotate_exclude(self):
+        self.assertQuerysetEqual(
+            CaseTestModel.objects.annotate(test=Case(
+                When(integer=1, then=Value('one')),
+                When(integer=2, then=Value('two')),
+                default=Value('other'),
+                output_field=models.CharField(),
+            )).exclude(test='other').order_by('pk'),
+            [(1, 'one'), (2, 'two'), (2, 'two')],
+            transform=attrgetter('integer', 'test')
+        )
+
     def test_combined_expression(self):
         self.assertQuerysetEqual(
             CaseTestModel.objects.annotate(