Fixed #25307 -- Fixed QuerySet.annotate() crash with conditional expressions.

Thanks Travis Newport for the tests and Josh Smeaton for contributing
to the patch.

2 files changed, 22 insertions, 1 deletions

diff --git a/django/db/models/sql/query.py b/django/db/models/sql/query.py
index 16ed92a4d4..5f65786373 100644
--- a/django/db/models/sql/query.py
+++ b/django/db/models/sql/query.py
@@ -18,6 +18,7 @@ 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.fields.related_lookups import MultiColSource
+from django.db.models.lookups import Lookup
 from django.db.models.query_utils import (
     Q, check_rel_lookup_compatibility, refs_expression,
 )
@@ -366,11 +367,20 @@ class Query(object):
         orig_exprs = annotation.get_source_expressions()
         new_exprs = []
         for expr in orig_exprs:
+            # FIXME: These conditions are fairly arbitrary. Identify a better
+            # method of having expressions decide which code path they should
+            # take.
             if isinstance(expr, Ref):
                 # Its already a Ref to subquery (see resolve_ref() for
                 # details)
                 new_exprs.append(expr)
-            elif isinstance(expr, Col):
+            elif isinstance(expr, (WhereNode, Lookup)):
+                # Decompose the subexpressions further. The code here is
+                # copied from the else clause, but this condition must appear
+                # before the contains_aggregate/is_summary condition below.
+                new_expr, col_cnt = self.rewrite_cols(expr, col_cnt)
+                new_exprs.append(new_expr)
+            elif isinstance(expr, Col) or (expr.contains_aggregate and not expr.is_summary):
                 # Reference to column. Make sure the referenced column
                 # is selected.
                 col_cnt += 1
diff --git a/django/db/models/sql/where.py b/django/db/models/sql/where.py
index df44803b8a..bb4e9252b4 100644
--- a/django/db/models/sql/where.py
+++ b/django/db/models/sql/where.py
@@ -118,6 +118,13 @@ class WhereNode(tree.Node):
             cols.extend(child.get_group_by_cols())
         return cols
 
+    def get_source_expressions(self):
+        return self.children[:]
+
+    def set_source_expressions(self, children):
+        assert len(children) == len(self.children)
+        self.children = children
+
     def relabel_aliases(self, change_map):
         """
         Relabels the alias values of any children. 'change_map' is a dictionary
@@ -160,6 +167,10 @@ class WhereNode(tree.Node):
     def contains_aggregate(self):
         return self._contains_aggregate(self)
 
+    @property
+    def is_summary(self):
+        return any(child.is_summary for child in self.children)
+
 
 class NothingNode(object):
     """