Fixed #5789 -- Changed LocaleMiddleware session variable to '_language'.

The old 'django_language' variable will still be read from in order
to migrate users. The backwards-compatability shim will be removed in
Django 1.8.

Thanks to jdunck for the report and stugots for the initial patch.

django/middleware/locale.py

@@ -56,8 +56,14 @@ class LocaleMiddleware(object):
                 return self.response_redirect_class(language_url)
 
         # Store language back into session if it is not present
-        if hasattr(request, 'session'):
-            request.session.setdefault('django_language', language)
+        if hasattr(request, 'session') and '_language' not in request.session:
+            # Backwards compatibility check on django_language (remove in 1.8);
+            # revert to: `request.session.setdefault('_language', language)`.
+            if 'django_language' in request.session:
+                request.session['_language'] = request.session['django_language']
+                del request.session['django_language']
+            else:
+                request.session['_language'] = language
 
         if not (self.is_language_prefix_patterns_used()
                 and language_from_path):

django/utils/translation/trans_real.py

@@ -426,7 +426,8 @@ def get_language_from_request(request, check_path=False):
             return lang_code
 
     if hasattr(request, 'session'):
-        lang_code = request.session.get('django_language', None)
+        # for backwards compatibility django_language is also checked (remove in 1.8)
+        lang_code = request.session.get('_language', request.session.get('django_language'))
         if lang_code in supported and lang_code is not None and check_for_language(lang_code):
             return lang_code
 

django/views/i18n.py

@@ -34,7 +34,7 @@ def set_language(request):
         lang_code = request.POST.get('language', None)
         if lang_code and check_for_language(lang_code):
             if hasattr(request, 'session'):
-                request.session['django_language'] = lang_code
+                request.session['_language'] = lang_code
             else:
                 response.set_cookie(settings.LANGUAGE_COOKIE_NAME, lang_code)
     return response