Implement ForeignKey support (does not support reverse relations)

modeltranslation/fields.py

@@ -25,6 +25,7 @@ SUPPORTED_FIELDS = (
     fields.TimeField,
     fields.files.FileField,
     fields.files.ImageField,
+    fields.related.ForeignKey,
 )
 try:
     SUPPORTED_FIELDS += (fields.GenericIPAddressField,)  # Django 1.4+ only
@@ -50,6 +51,8 @@ def create_translation_field(model, field_name, lang):
     if not (isinstance(field, SUPPORTED_FIELDS) or cls_name in mt_settings.CUSTOM_FIELDS):
         raise ImproperlyConfigured(
             '%s is not supported by modeltranslation.' % cls_name)
+    if isinstance(field, fields.related.ForeignKey) and field.rel.related_name != '+':
+        raise ImproperlyConfigured('Translated ForeignKey fields must use related_name="+"')
     translation_class = field_factory(field.__class__)
     return translation_class(translated_field=field, language=lang)
 
@@ -127,8 +130,10 @@ class TranslationField(object):
 
     def get_attname_column(self):
         attname = self.get_attname()
-        column = build_localized_fieldname(
-            self.translated_field.db_column or self.translated_field.name, self.language) or attname
+        if self.translated_field.db_column:
+            column = build_localized_fieldname(self.translated_field.db_column)
+        else:
+            column = attname
         return attname, column
 
     def south_field_triple(self):
@@ -137,8 +142,12 @@ class TranslationField(object):
         """
         # We'll just introspect the _actual_ field.
         from south.modelsinspector import introspector
-        field_class = '%s.%s' % (self.translated_field.__class__.__module__,
-                                 self.translated_field.__class__.__name__)
+        try:
+            # Check if the field provides its own 'field_class':
+            field_class = self.translated_field.south_field_triple()[0]
+        except AttributeError:
+            field_class = '%s.%s' % (self.translated_field.__class__.__module__,
+                                     self.translated_field.__class__.__name__)
         args, kwargs = introspector(self)
         # That's our definition!
         return (field_class, args, kwargs)

modeltranslation/tests/__init__.py

@@ -43,8 +43,8 @@ except ImportError:
 # so we'll just pass in None.
 request = None
 
-# How much models are registered for tests.
-TEST_MODELS = 22
+# How many models are registered for tests.
+TEST_MODELS = 23
 
 
 class reload_override_settings(override_settings):
@@ -619,6 +619,64 @@ class FileFieldsTest(ModeltranslationTestBase):
         inst.image_de.delete()
 
 
+class ForeignKeyFieldsTest(ModeltranslationTestBase):
+
+    def test_translated_models(self):
+        field_names = dir(models.ForeignKeyModel())
+        self.failUnless('id' in field_names)
+        for f in ('test', 'test_de', 'test_en', 'optional', 'optional_en', 'optional_de'):
+            self.failUnless(f in field_names)
+            self.failUnless('%s_id' % f in field_names)
+
+    def test_db_column_names(self):
+        meta = models.ForeignKeyModel._meta
+
+        # Make sure the correct database columns always get used:
+        attname, col = meta.get_field('test').get_attname_column()
+        self.failUnlessEqual(attname, 'test_id')
+        self.failUnlessEqual(attname, col)
+
+        attname, col = meta.get_field('test_en').get_attname_column()
+        self.failUnlessEqual(attname, 'test_en_id')
+        self.failUnlessEqual(attname, col)
+
+        attname, col = meta.get_field('test_de').get_attname_column()
+        self.failUnlessEqual(attname, 'test_de_id')
+        self.failUnlessEqual(attname, col)
+
+    def test_translated_models_instance(self):
+        test_inst1 = models.TestModel(title_en='title1_en', title_de='title1_de')
+        test_inst1.save()
+        test_inst2 = models.TestModel(title_en='title2_en', title_de='title2_de')
+        test_inst2.save()
+        inst = models.ForeignKeyModel()
+
+        trans_real.activate("de")
+        inst.test = test_inst1
+        inst.optional = None
+
+        trans_real.activate("en")
+        inst.optional = test_inst2
+        inst.save()
+
+        trans_real.activate("de")
+        self.failUnlessEqual(inst.test.title, 'title1_de')
+        self.failUnlessEqual(inst.test_de_id, test_inst1.pk)
+        self.failUnlessEqual(inst.test_de.title, 'title1_de')
+        self.failUnlessEqual(inst.optional, None)
+
+        # Test fallbacks:
+        trans_real.activate("en")
+        with default_fallback():
+            self.failUnlessEqual(inst.test.pk, test_inst1.pk)
+            self.failUnlessEqual(inst.test.title, 'title1_en')
+
+        # Test English:
+        self.failUnlessEqual(inst.optional.title, 'title2_en')
+        self.failUnlessEqual(inst.optional_en_id, test_inst2.pk)
+        self.failUnlessEqual(inst.optional_en.title, 'title2_en')
+
+
 class OtherFieldsTest(ModeltranslationTestBase):
     def test_translated_models(self):
         inst = models.OtherFieldsModel.objects.create()

modeltranslation/tests/models.py

@@ -34,6 +34,11 @@ class FileFieldsModel(models.Model):
     file = models.FileField(upload_to='modeltranslation_tests', null=True, blank=True)
     image = models.ImageField(upload_to='modeltranslation_tests', null=True, blank=True)
 
+########## Foreign Key fields testing
+
+class ForeignKeyModel(models.Model):
+    test = models.ForeignKey(TestModel, null=True, related_name="+")
+    optional = models.ForeignKey(TestModel, blank=True, null=True, related_name="+")
 
 ########## Custom fields testing
 

modeltranslation/tests/translation.py

@@ -3,10 +3,10 @@ from django.utils.translation import ugettext_lazy
 
 from modeltranslation.translator import translator, TranslationOptions
 from modeltranslation.tests.models import (
-    TestModel, FallbackModel, FallbackModel2, FileFieldsModel, OtherFieldsModel, DescriptorModel,
-    AbstractModelA, AbstractModelB, Slugged, MetaData, Displayable, Page, RichText, RichTextPage,
-    MultitableModelA, MultitableModelB, MultitableModelC, ManagerTestModel, CustomManagerTestModel,
-    CustomManager2TestModel, GroupFieldsetsModel, NameModel)
+    TestModel, FallbackModel, FallbackModel2, FileFieldsModel, ForeignKeyModel, OtherFieldsModel,
+    DescriptorModel, AbstractModelA, AbstractModelB, Slugged, MetaData, Displayable, Page,
+    RichText, RichTextPage, MultitableModelA, MultitableModelB, MultitableModelC, ManagerTestModel,
+    CustomManagerTestModel, CustomManager2TestModel, GroupFieldsetsModel, NameModel)
 
 
 class TestTranslationOptions(TranslationOptions):
@@ -35,6 +35,13 @@ class FileFieldsModelTranslationOptions(TranslationOptions):
 translator.register(FileFieldsModel, FileFieldsModelTranslationOptions)
 
 
+########## Foreign Key fields testing
+
+class ForeignKeyModelTranslationOptions(TranslationOptions):
+    fields = ('test', 'optional',)
+translator.register(ForeignKeyModel, ForeignKeyModelTranslationOptions)
+
+
 ########## Custom fields testing
 
 class OtherFieldsModelTranslationOptions(TranslationOptions):