Fixed #22135 -- Added ModelAdmin.get_changeform_initial_data().

Allows custom behavior for setting initial form data in ModelAdmin.
By default, initial data is set via GET params. The new method allows
this behavior to be overridden.

Thanks egasimus for the suggestion.

tests/admin_views/admin.py

@@ -796,6 +796,10 @@ class RestaurantAdmin(admin.ModelAdmin):
     inlines = [WorkerInlineAdmin]
     view_on_site = False
 
+    def get_changeform_initial_data(self, request):
+        return {'name': 'overridden_value'}
+
+
 site = admin.AdminSite(name="admin")
 site.register(Article, ArticleAdmin)
 site.register(CustomArticle, CustomArticleAdmin)

tests/admin_views/tests.py

@@ -765,6 +765,19 @@ class AdminViewFormUrlTest(TestCase):
         self.assertTrue('form_url' in response.context, msg='form_url not present in response.context')
         self.assertEqual(response.context['form_url'], 'pony')
 
+    def testInitialDataCanBeOverridden(self):
+        """
+        Tests that the behavior for setting initial
+        form data can be overridden in the ModelAdmin class.
+
+        Usually, the initial value is set via the GET params.
+        """
+        response = self.client.get('/test_admin/%s/admin_views/restaurant/add/' % self.urlbit, {'name': 'test_value'})
+        # this would be the usual behaviour
+        self.assertNotContains(response, 'value="test_value"')
+        # this is the overridden behaviour
+        self.assertContains(response, 'value="overridden_value"')
+
 
 @override_settings(PASSWORD_HASHERS=('django.contrib.auth.hashers.SHA1PasswordHasher',))
 class AdminJavaScriptTest(TestCase):