Exclude m2m fields in TranslationsMixin.update_translations. Fixes Kr…

…istianOellegaard#285.

docs/public/release_notes.rst

@@ -2,10 +2,23 @@
 Release Notes
 #############
 
+.. release 1.5.1
+
+*****************************
+1.5.1 - current release
+*****************************
+
+Fixes:
+
+- Filter out m2m and generic fields in
+  :meth:`~hvad.contrib.restframework.serializers.TranslationsMixin.update_translation`
+  so it does not bite when using (unsupported) m2m fields or generic relations in a
+  translation — :issue:`285`.
+
 .. release 1.5.0
 
 *****************************
-1.5.0 - current release
+1.5.0
 *****************************
 
 Released on February 2, 2016

hvad/contrib/restframework/serializers.py

@@ -134,16 +134,23 @@ def update(self, instance, data):
 
     def update_translation(self, instance, data):
         if django.VERSION >= (1, 8):
-            fields = [field.name for field in self.Meta.model._meta.translations_model._meta.get_fields()
-                      if field.name not in ('id', 'master', 'language_code')]
+            fields = set(field.name
+                         for field in self.Meta.model._meta.translations_model._meta.get_fields()
+                         if not field.is_relation or                    # regular fields are ok
+                            field.one_to_one or                         # one to one is ok
+                            field.many_to_one and field.related_model)  # many_to_one only if not generic
         else:
-            fields = [name for name in self.Meta.model._meta.translations_model._meta.get_all_field_names()
-                      if name not in ('id', 'master', 'master_id', 'language_code')]
+            fields = set(name
+                         for name in self.Meta.model._meta.translations_model._meta.get_all_field_names())
+        fields.intersection_update(data)
+        vetoed = fields.intersection('id', 'master', 'master_id', 'language_code')
+        if vetoed:
+            raise KeyError('These fields are not allowed in data: ' % ', '.join(vetoed))
+
         for key, value in data.items():
             setattr(instance, key, value)
         instance.save(update_fields=fields)
 
-
 #=============================================================================
 
 class TranslatableModelMixin(object):

hvad/test_utils/project/app/models.py

@@ -2,6 +2,7 @@
 from django.template.defaultfilters import slugify
 from hvad.models import TranslatableModel, TranslatedFields
 from hvad.manager import TranslationManager, TranslationQueryset
+from hvad.utils import get_cached_translation
 from django.utils.encoding import python_2_unicode_compatible
 
 #===============================================================================
@@ -101,6 +102,23 @@ def __str__(self):
         return self.name
 
 
+@python_2_unicode_compatible
+class TranslatedMany(TranslatableModel):
+    """ WARNING: this is not officially supported. This test model is more
+        of a monitor so we know what we break, than a promise not to break it.
+    """
+    name = models.CharField(max_length=128)
+    translations = TranslatedFields(
+        translated_field = models.CharField(max_length=128),
+        many = models.ManyToManyField(Normal, related_name='translated_many'),
+    )
+
+    def __str__(self):
+        return ('%s, %s <%s>' % (self.name, self.translated_field, self.language_code)
+                if get_cached_translation(self) is not None
+                else '%s <none>' % self.name)
+
+
 class Standard(models.Model):
     """ Untranslatable Model with foreign key to Normal """
     normal_field = models.CharField(max_length=255)

hvad/tests/contrib/restframework.py

@@ -2,7 +2,7 @@
 from rest_framework.serializers import ModelSerializer, CharField
 from hvad.test_utils.context_managers import LanguageOverride
 from hvad.test_utils.testcase import HvadTestCase
-from hvad.test_utils.project.app.models import Normal, Related
+from hvad.test_utils.project.app.models import Normal, Related, TranslatedMany
 from hvad.test_utils.data import NORMAL
 from hvad.test_utils.fixtures import NormalFixture
 from hvad.contrib.restframework import (TranslationsMixin,
@@ -420,6 +420,35 @@ def test_update_partial(self):
         qs = Normal.objects.language('all').filter(pk=self.normal_id[1], shared_field='shared')
         self.assertCountEqual([obj.language_code for obj in qs], self.translations)
 
+    def test_update_translated_many(self):
+        'Update an existing instance, with an excluded translated M2M field'
+        """ WARNING - this is unsupported, this test case is here so we know
+            what we break rather than to enforce that behavior
+        """
+        obj = TranslatedMany.objects.language('en').create(name='shared', translated_field='English')
+        # reload with normal caching conditions so query counting works
+        obj = TranslatedMany.objects.untranslated().prefetch_related('translations').get(pk=obj.pk)
+        data = {
+            'name': 'shared-updated',
+            'translations': {
+                'en': {'translated_field': u'English-updated'},
+                'fr': {'translated_field': u'French-added'},
+            },
+        }
+        class TranslationSerializerClass(ModelSerializer):
+            class Meta:
+                exclude = ['many']
+        class SerializerClass(TranslationsMixin, ModelSerializer):
+            class Meta:
+                model = TranslatedMany
+                translations_serializer = TranslationSerializerClass
+
+        serializer = SerializerClass(instance=obj, data=data)
+        self.assertTrue(serializer.is_valid())
+        with self.assertNumQueries(4):  # update shared, update en, insert fr
+                                        # select to delete (none so no actual delete after)
+            serializer.save()
+
 #=============================================================================
 
 class CombinedTests(HvadTestCase, NormalFixture):