fix implementation of order_by

tof/managers.py

@@ -3,6 +3,9 @@
 # @Date:   2019-11-17 15:02:55
 # @Last Modified by:   MaxST
 # @Last Modified time: 2019-11-19 16:40:49
+from django.contrib.contenttypes.models import ContentType
+from django.utils.translation import get_language
+from django.db.models import Case, When, Exists, F, OuterRef, Subquery
 from django.db import models
 
 from .decorators import tof_filter, tof_prefetch
@@ -21,6 +24,38 @@ def exclude(self, *args, **kwargs):
     def get(self, *args, **kwargs):
         return super().get(*args, **kwargs)
 
+    @tof_filter  # noqa
+    def order_by(self, *args):
+        from .models import Translation
+
+        content_type = ContentType.objects.get_for_model(self.model)
+
+        new_args = []
+        for arg in args:
+            field_name, order = arg, ''
+            if arg.startswith('-') or arg.startswith('+'):
+                field_name, order = arg[1:], arg[0]
+
+            if field_name == '?':
+                new_args.append('?')
+                continue
+
+            new_args.append(f'{order}_{field_name}')
+
+            translation = Translation.objects.filter(content_type=content_type, lang=get_language(),
+                                                     field__name=field_name)
+
+            self = self.annotate(**{f'_{field_name}': Case(
+                When(
+                    Exists(translation.filter(object_id=OuterRef('pk'))),
+                    then=Subquery(translation.filter(object_id=OuterRef('pk')).values('value'))
+                ),
+                default=F(field_name),
+                output_field=models.CharField(),
+            )})
+
+        return super().order_by(*new_args)
+
 
 class TranslationsQuerySet(DecoratedMixIn, models.QuerySet):
     pass

tof/tests/tests.py

@@ -210,6 +210,95 @@ def test_behavior(self):
             self.assertEqual(wine1, serch_wine)
 
 
+class OrderByTestCase(TestCase):
+    @classmethod
+    def setUpTestData(cls):
+        clean_model(Wine)
+
+        cls.wine1 = mixer.blend(Wine, title='Wine 1', temperature_from=10)
+        cls.wine2 = mixer.blend(Wine, title='Wine 2', temperature_from=20)
+
+        ct = ContentType.objects.get_for_model(Wine)
+        fld = mixer.blend(TranslatableField, name='title', title='title', content_type=ct)
+        fld2 = mixer.blend(TranslatableField, name='description', title='description', content_type=ct)
+
+        lang_en = Language.objects.get(iso='en')
+
+        mixer.blend(Translation, content_object=cls.wine1, field=fld, lang=lang_en, value='Wine 1 title')
+        mixer.blend(Translation, content_object=cls.wine1, field=fld2, lang=lang_en, value='Wine 2 desc')
+
+        mixer.blend(Translation, content_object=cls.wine2, field=fld, lang=lang_en, value='Wine 2 title')
+        mixer.blend(Translation, content_object=cls.wine2, field=fld2, lang=lang_en, value='Wine 2 desc')
+
+    def test_order_by_one_field_asc(self):
+        ordered_wines = [wine for wine in Wine.objects.order_by('title')]
+        expected_ordered_wines = [self.wine1, self.wine2]
+
+        self.assertEqual(ordered_wines, expected_ordered_wines)
+
+        ordered_wines = [wine for wine in Wine.objects.order_by('description')]
+        expected_ordered_wines = [self.wine1, self.wine2]
+
+        self.assertEqual(ordered_wines, expected_ordered_wines)
+
+    def test_order_by_one_field_desc(self):
+        ordered_wines = [wine for wine in Wine.objects.order_by('-title')]
+        expected_ordered_wines = [self.wine2, self.wine1]
+
+        self.assertEqual(ordered_wines, expected_ordered_wines)
+
+        ordered_wines = [wine for wine in Wine.objects.order_by('-description')]
+        expected_ordered_wines = [self.wine1, self.wine2]
+
+        self.assertEqual(ordered_wines, expected_ordered_wines)
+
+    def test_order_by_two_fields_asc(self):
+        ordered_wines = [wine for wine in Wine.objects.order_by('description', 'title')]
+        expected_ordered_wines = [self.wine1, self.wine2]
+
+        self.assertEqual(ordered_wines, expected_ordered_wines)
+
+        ordered_wines = [wine for wine in Wine.objects.order_by('-description', 'title')]
+        expected_ordered_wines = [self.wine1, self.wine2]
+
+        self.assertEqual(ordered_wines, expected_ordered_wines)
+
+    def test_order_by_two_fields_desc(self):
+        ordered_wines = [wine for wine in Wine.objects.order_by('-description', '-title')]
+        expected_ordered_wines = [self.wine2, self.wine1]
+
+        self.assertEqual(ordered_wines , expected_ordered_wines)
+
+        ordered_wines = [wine for wine in Wine.objects.order_by('description', '-title')]
+        expected_ordered_wines = [self.wine2, self.wine1]
+
+        self.assertEqual(ordered_wines, expected_ordered_wines)
+
+    def test_order_by_random(self):
+        ordered_wines = [wine for wine in Wine.objects.order_by('?')]
+        expected_ordered_wines_1 = [self.wine1, self.wine2]
+        expected_ordered_wines_2 = [self.wine2, self.wine1]
+
+        self.assertTrue(ordered_wines == expected_ordered_wines_1 or ordered_wines == expected_ordered_wines_2)
+
+    def test_order_by_two_order_by(self):
+        ordered_wines = [wine for wine in Wine.objects.order_by('title').order_by('description')]
+        expected_ordered_wines = [self.wine1, self.wine2]
+
+        self.assertEqual(ordered_wines, expected_ordered_wines)
+
+        ordered_wines = [wine for wine in Wine.objects.order_by('description').order_by('title')]
+        expected_ordered_wines = [self.wine1, self.wine2]
+
+        self.assertEqual(ordered_wines, expected_ordered_wines)
+
+    def test_order_by_with_no_translatable_field(self):
+        ordered_wines = [wine for wine in Wine.objects.order_by('-temperature_from', 'title')]
+        expected_ordered_wines = [self.wine2, self.wine1]
+
+        self.assertEqual(ordered_wines, expected_ordered_wines)
+
+
 class TranslatableTextTestCase(TestCase):
     @classmethod
     def setUpTestData(cls):