Merge pull request #21320 from edx/ormsbee/theme_by_qs

Override theme with site_theme query param

openedx/core/djangoapps/theming/middleware.py

@@ -21,9 +21,15 @@ class CurrentSiteThemeMiddleware(object):
         """
         Set the request's 'site_theme' attribute based upon the current user.
         """
+        # Specifying a "site_theme" querystring param takes precedence
+        qs_theme = request.GET.get('site_theme')
+
         # Determine if the user has specified a preview site
         preview_site_theme = get_user_preview_site_theme(request)
-        if preview_site_theme:
+
+        if qs_theme:
+            site_theme = SiteTheme(site=request.site, theme_dir_name=qs_theme)
+        elif preview_site_theme:
             site_theme = preview_site_theme
         else:
             default_theme = None

openedx/core/djangoapps/theming/tests/test_middleware.py

@@ -30,11 +30,16 @@ class TestCurrentSiteThemeMiddleware(TestCase):
         self.site_theme_middleware = CurrentSiteThemeMiddleware()
         self.user = UserFactory.create()
 
-    def create_mock_get_request(self):
+    def create_mock_get_request(self, qs_theme=None):
         """
         Returns a mock GET request.
         """
-        request = RequestFactory().get(TEST_URL)
+        if qs_theme:
+            test_url = "{}?site_theme={}".format(TEST_URL, qs_theme)
+        else:
+            test_url = TEST_URL
+
+        request = RequestFactory().get(test_url)
         self.initialize_mock_request(request)
         return request
 
@@ -87,7 +92,12 @@ class TestCurrentSiteThemeMiddleware(TestCase):
         self.initialize_mock_request(post_request)
         set_user_preview_site_theme(post_request, None)
 
-        # Finally verify that no theme is returned
+        # Verify that no theme is returned now
         get_request = self.create_mock_get_request()
         self.assertEqual(self.site_theme_middleware.process_request(get_request), None)
         self.assertIsNone(get_request.site_theme)
+
+        # Verify that we can still force the theme with a querystring arg
+        get_request = self.create_mock_get_request(qs_theme=TEST_THEME_NAME)
+        self.assertEqual(self.site_theme_middleware.process_request(get_request), None)
+        self.assertEqual(get_request.site_theme.theme_dir_name, TEST_THEME_NAME)