utils: fix get_templated_url to work with packed contexts (#16308)

combo/utils.py

@@ -35,6 +35,7 @@ from requests import Response, Session as RequestsSession
 
 from django.conf import settings
 from django.core.cache import cache
+from django.template import Context
 from django.utils.html import strip_tags
 from django.utils.http import urlencode, quote
 
@@ -174,9 +175,9 @@ class UnknownTemplateVariableError(KeyError):
     pass
 
 def get_templated_url(url, context=None):
-    template_vars = {}
+    template_vars = Context()
     if context:
-        template_vars.update(context.flatten())
+        template_vars.update(context)
         user = getattr(context.get('request'), 'user', None)
         if user and user.is_authenticated():
             template_vars['user_email'] = quote(user.email)

tests/test_utils.py

@@ -87,3 +87,12 @@ def test_templated_url():
         assert get_templated_url('[test_url]/[foobar]/?NameID=[user_nameid]&email=[user_email]',
                                  context=context) == \
                 'http://www.example.net/barfoo/?NameID=r2%26d2&email=foo%3D3%40example.net'
+
+    # packed contexts
+    request = RequestFactory().get('/')
+    request.user = None
+    context = Context({'request': request})
+    context.update({'foo': 'bar'})
+    ctx = Context()
+    ctx.update(context)
+    assert get_templated_url('[foo]', context=ctx) == 'bar'