Fixed #5651 -- Correctly get language from request (#5664)

If for some reason local variable language becomes empty string instead of None then treat is as None. (Duck typing)

Fixes #5651

CHANGELOG.txt

@@ -43,6 +43,7 @@
 * Fixed a bug where moving a published page under a page marked as pending publishing
   is left as published instead of being marked as pending publishing.
 * Fixed AttributeError when using ``create_page`` in management command
+* Fixed a bug in getting the language from current request which can cause error 500
 
 
 === 3.3.2 (2016-08-11) ===

cms/tests/test_i18n.py

@@ -6,7 +6,7 @@
 
 from cms import api
 from cms.test_utils.testcases import CMSTestCase
-from cms.utils import i18n
+from cms.utils import i18n, get_language_from_request
 
 
 @override_settings(
@@ -371,3 +371,39 @@ def test_session_language(self):
         response = self.client.get('/')
         self.assertEqual(response.status_code, 302)
         self.assertRedirects(response, '/en/')
+
+
+@override_settings(
+    LANGUAGE_CODE='en',
+    LANGUAGES=(('fr', 'French'),
+               ('en', 'English'),
+               ('de', 'German'),
+               ('es', 'Spanish')),
+    CMS_LANGUAGES={
+        1: [{'code' : 'en',
+             'name': 'English',
+             'public': False},
+            {'code': 'fr',
+             'name': 'French',
+             'public': True},
+        ],
+        'default': {
+            'fallbacks': ['en', 'fr'],
+            'redirect_on_fallback': False,
+            'public': True,
+            'hide_untranslated': False,
+        }
+    },
+    SITE_ID=1,
+)
+class TestGetLanguageFromRequest(CMSTestCase):
+
+    def test_get_language_from_request_does_not_return_empty_string_from_post(self):
+        request = self.get_request(language='en', post_data={
+            'language': '',
+        })
+        self.assertEqual(get_language_from_request(request), 'en')
+
+    def test_get_language_from_request_does_not_return_empty_string_from_get(self):
+        request = self.get_request('/en/?language=', language='en')
+        self.assertEqual(get_language_from_request(request), 'en')

cms/utils/__init__.py

@@ -52,20 +52,20 @@ def get_language_from_request(request, current_page=None):
         language = get_language_code(language)
         if not language in get_language_list(site_id):
             language = None
-    if language is None:
+    if not language:
         language = get_language_code(getattr(request, 'LANGUAGE_CODE', None))
     if language:
         if not language in get_language_list(site_id):
             language = None
 
-    if language is None and current_page:
+    if not language and current_page:
         # in last resort, get the first language available in the page
         languages = current_page.get_languages()
 
         if len(languages) > 0:
             language = languages[0]
 
-    if language is None:
+    if not language:
         # language must be defined in CMS_LANGUAGES, so check first if there
         # is any language with LANGUAGE_CODE, otherwise try to split it and find
         # best match