Extend jinja2 nested undefined support to keys/indices (#55094)

changelogs/fragments/jinja2_nested_undefined_getitem.yaml

@@ -0,0 +1,2 @@
+minor_changes:
+- jinja2 - accesses to keys/indices on an undefined value now return further undefined values rather than throwing an exception

lib/ansible/template/__init__.py

@@ -207,6 +207,10 @@ class AnsibleUndefined(StrictUndefined):
         # Return original Undefined object to preserve the first failure context
         return self
 
+    def __getitem__(self, key):
+        # Return original Undefined object to preserve the first failure context
+        return self
+
     def __repr__(self):
         return 'AnsibleUndefined'
 

test/integration/targets/template/tasks/main.yml

@@ -666,6 +666,24 @@
       - list_var.0.foo.bar | default('DEFAULT') == 'DEFAULT'
       - list_var.1.foo is not defined
       - list_var.1.foo | default('DEFAULT') == 'DEFAULT'
+      - dict_var is defined
+      - dict_var['bar'] is defined
+      - dict_var['bar']['baz'] is not defined
+      - dict_var['bar']['baz'] | default('DEFAULT') == 'DEFAULT'
+      - dict_var['bar']['baz']['abc'] is not defined
+      - dict_var['bar']['baz']['abc'] | default('DEFAULT') == 'DEFAULT'
+      - dict_var['baz'] is not defined
+      - dict_var['baz']['abc'] is not defined
+      - dict_var['baz']['abc'] | default('DEFAULT') == 'DEFAULT'
+      - list_var[0] is defined
+      - list_var[1] is not defined
+      - list_var[0]['foo'] is defined
+      - list_var[0]['foo']['bar'] is not defined
+      - list_var[0]['foo']['bar'] | default('DEFAULT') == 'DEFAULT'
+      - list_var[1]['foo'] is not defined
+      - list_var[1]['foo'] | default('DEFAULT') == 'DEFAULT'
+      - dict_var['bar'].baz is not defined
+      - dict_var['bar'].baz | default('DEFAULT') == 'DEFAULT'
 
 - template:
     src: template_destpath_test.j2