Add support for localized query look ups

Author: Oliver Sauder

README.rst

@@ -348,6 +348,7 @@ Experimental feature
 ^^^^^^^^^^^^^^^^^^^^
 Enables the following experimental features:
     * ``LocalizedField`` will return ``None`` instead of an empty ``LocalizedValue`` if there is no database value.
+    * ``LocalizedField`` lookups will lookup by currently active language instead of HStoreField
 
 .. code-block:: python
 

localized_fields/__init__.py

@@ -0,0 +1 @@
+default_app_config = 'localized_fields.apps.LocalizedFieldsConfig'

localized_fields/apps.py

@@ -1,5 +1,21 @@
+import inspect
+
 from django.apps import AppConfig
+from django.conf import settings
+
+from . import lookups
+from .fields import LocalizedField
+from .lookups import LocalizedLookupMixin
 
 
 class LocalizedFieldsConfig(AppConfig):
     name = 'localized_fields'
+
+    def ready(self):
+        if getattr(settings, 'LOCALIZED_FIELDS_EXPERIMENTAL', False):
+            for _, clazz in inspect.getmembers(lookups):
+                if not inspect.isclass(clazz) or clazz is LocalizedLookupMixin:
+                    continue
+
+                if issubclass(clazz, LocalizedLookupMixin):
+                    LocalizedField.register_lookup(clazz)

localized_fields/lookups.py

@@ -0,0 +1,78 @@
+from django.conf import settings
+from django.contrib.postgres.fields.hstore import KeyTransform
+from django.contrib.postgres.lookups import (SearchLookup, TrigramSimilar,
+                                             Unaccent,)
+from django.db.models.lookups import (Contains, EndsWith, Exact, IContains,
+                                      IEndsWith, IExact, In, IRegex, IsNull,
+                                      IStartsWith, Regex, StartsWith,)
+from django.utils import translation
+
+
+class LocalizedLookupMixin():
+    def process_lhs(self, qn, connection):
+        language = translation.get_language() or settings.LANGUAGE_CODE
+        self.lhs = KeyTransform(language, self.lhs)
+        return super().process_lhs(qn, connection)
+
+    def get_prep_lookup(self):
+        return str(self.rhs)
+
+
+class LocalizedSearchLookup(LocalizedLookupMixin, SearchLookup):
+    pass
+
+
+class LocalizedUnaccent(LocalizedLookupMixin, Unaccent):
+    pass
+
+
+class LocalizedTrigramSimilair(LocalizedLookupMixin, TrigramSimilar):
+    pass
+
+
+class LocalizedExact(LocalizedLookupMixin, Exact):
+    pass
+
+
+class LocalizedIExact(LocalizedLookupMixin, IExact):
+    pass
+
+
+class LocalizedIn(LocalizedLookupMixin, In):
+    pass
+
+
+class LocalizedContains(LocalizedLookupMixin, Contains):
+    pass
+
+
+class LocalizedIContains(LocalizedLookupMixin, IContains):
+    pass
+
+
+class LocalizedStartsWith(LocalizedLookupMixin, StartsWith):
+    pass
+
+
+class LocalizedIStartsWith(LocalizedLookupMixin, IStartsWith):
+    pass
+
+
+class LocalizedEndsWith(LocalizedLookupMixin, EndsWith):
+    pass
+
+
+class LocalizedIEndsWith(LocalizedLookupMixin, IEndsWith):
+    pass
+
+
+class LocalizedIsNullWith(LocalizedLookupMixin, IsNull):
+    pass
+
+
+class LocalizedRegexWith(LocalizedLookupMixin, Regex):
+    pass
+
+
+class LocalizedIRegexWith(LocalizedLookupMixin, IRegex):
+    pass

tests/test_lookups.py

@@ -0,0 +1,51 @@
+from django.apps import apps
+from django.conf import settings
+from django.test import TestCase, override_settings
+from django.utils import translation
+
+from localized_fields.fields import LocalizedField
+from localized_fields.value import LocalizedValue
+
+from .fake_model import get_fake_model
+
+
+@override_settings(LOCALIZED_FIELDS_EXPERIMENTAL=True)
+class LocalizedLookupsTestCase(TestCase):
+    """Tests whether localized lookups properly work with."""
+    TestModel1 = None
+
+    @classmethod
+    def setUpClass(cls):
+        """Creates the test model in the database."""
+
+        super(LocalizedLookupsTestCase, cls).setUpClass()
+
+        # reload app as setting has changed
+        config = apps.get_app_config('localized_fields')
+        config.ready()
+
+        cls.TestModel = get_fake_model(
+            {
+                'text': LocalizedField(),
+            }
+        )
+
+    def test_localized_lookup(self):
+        """Tests whether localized lookup properly works."""
+
+        self.TestModel.objects.create(
+            text=LocalizedValue(dict(en='text_en', ro='text_ro', nl='text_nl')),
+        )
+
+        # assert that it properly lookups the currently active language
+        for lang_code, _ in settings.LANGUAGES:
+            translation.activate(lang_code)
+            assert self.TestModel.objects.filter(text='text_' + lang_code).exists()
+
+        # ensure that the default language is used in case no
+        # language is active at all
+        translation.deactivate_all()
+        assert self.TestModel.objects.filter(text='text_en').exists()
+
+        # ensure that hstore lookups still work
+        assert self.TestModel.objects.filter(text__ro='text_ro').exists()