Patch form_url in render_change_form so it carries over the language tab selection.

This is required, otherwise it gets lost if form_url is not empty.
Fixes #202, closes #204.

Author: spectras

docs/public/release_notes.rst

@@ -14,6 +14,8 @@ Fixes:
   not break anymore. — :issue:`206`.
 - Language tabs URI are now correctly generated when changelist filters are used.
   — :issue:`203`.
+- Admin language tab selection is no longer lost when change filters are active.
+  — :issue:`202`.
 
 .. release 0.5.0
 

hvad/admin.py

@@ -17,7 +17,7 @@
     from django.forms.utils import ErrorList
 else:
     from django.forms.util import ErrorList
-from django.http import Http404, HttpResponseRedirect
+from django.http import Http404, HttpResponseRedirect, QueryDict
 from django.shortcuts import render_to_response
 from django.template import TemplateDoesNotExist
 from django.template.context import RequestContext
@@ -27,7 +27,7 @@
 from django.utils.translation import ugettext_lazy as _, get_language
 from functools import update_wrapper
 from hvad.compat.force_unicode import force_unicode
-from hvad.compat.urls import urlencode
+from hvad.compat.urls import urlencode, urlparse
 from hvad.forms import TranslatableModelForm, translatable_inlineformset_factory, translatable_modelform_factory
 from hvad.utils import get_cached_translation, get_translation
 from hvad.manager import FALLBACK_LANGUAGES
@@ -225,6 +225,16 @@ def render_change_form(self, request, context, add=False, change=False,
         context['allow_deletion'] = len(available_languages) > 1
         context['language_tabs'] = self.get_language_tabs(request, available_languages)
         context['base_template'] = self.get_change_form_base_template()
+
+        # Ensure form action url carries over tab language
+        qs_language = request.GET.get('language')
+        if qs_language:
+            form_url = urlparse(form_url or request.get_full_path())
+            query = QueryDict(form_url.query, mutable=True)
+            if 'language' not in query:
+                query['language'] = qs_language
+            form_url = form_url._replace(query=query.urlencode()).geturl()
+
         return super(TranslatableAdmin, self).render_change_form(request,
                                                                   context,
                                                                   add, change,

hvad/tests/admin.py

@@ -9,6 +9,7 @@
 from django.http import HttpResponseForbidden, HttpResponseRedirect, QueryDict
 from hvad.admin import InlineModelForm
 from hvad.admin import translatable_modelform_factory
+from hvad.compat.urls import urlparse
 from hvad.forms import TranslatableModelForm
 from hvad.test_utils.context_managers import LanguageOverride
 from hvad.test_utils.fixtures import NormalFixture, SuperuserFixture
@@ -232,28 +233,44 @@ def test_admin_change_form_title(self):
                 self.assertTrue('en' in response.content.decode('utf-8'))
 
     def test_admin_change_form_language_tabs_urls(self):
-        from hvad.compat.urls import urlparse
-
         with LanguageOverride('en'):
             with self.login_user_context(username='admin', password='admin'):
                 get_url = reverse('admin:app_normal_change', args=(self.normal_id[1],))
                 test_urls = [
                     '%s?%s' % (get_url, '_changelist_filters=q%3Dsearchparam'),
+                    '%s?%s' % (get_url, '_changelist_filters=q%3Dsearchparam&language=fr'),
                 ]
 
                 for test_url in test_urls:
                     response = self.client.get(test_url)
                     self.assertEqual(response.status_code, 200)
                     tabs = response.context['language_tabs']
 
-                    test_querydict = QueryDict(urlparse(test_url).query, mutable=True)
+                    expected_querydict = QueryDict(urlparse(test_url).query, mutable=True)
 
                     for actual_tab_url, name, key, status in tabs:
-                        expected_querydict = test_querydict.copy()
                         expected_querydict['language'] = key
                         actual_querydict = QueryDict(urlparse(actual_tab_url).query)
                         self.assertEqual(expected_querydict, actual_querydict)
 
+    def test_admin_change_form_action_url(self):
+        with LanguageOverride('en'):
+            with self.login_user_context(username='admin', password='admin'):
+                url = reverse('admin:app_normal_change', args=(self.normal_id[1],))
+                tests = (
+                    '',
+                    'language=fr',
+                    '_changelist_filters=q%3Dparam&language=fr',
+                )
+                for query_string in tests:
+                    expected_dict = QueryDict(query_string)
+                    full_url = '%s?%s' % (url, query_string) if query_string else url
+                    response = self.client.get(full_url)
+                    form_url = urlparse(response.context['form_url'])
+                    self.assertEqual(expected_dict, QueryDict(form_url.query),
+                                     'query_string=%r' % query_string)
+
+
     def test_admin_change_form_redirect_add_another(self):
         lang = 'en'
         with LanguageOverride('ja'):