wip: Try using localized_cached_property for cache_name

modeltranslation/fields.py

@@ -482,17 +482,3 @@ def __set__(self, instance, value):
         loc_field_name = build_localized_fieldname(self.field_name, get_language())
         loc_attname = instance._meta.get_field(loc_field_name).get_attname()
         setattr(instance, loc_attname, value)
-
-
-class LanguageCacheSingleObjectDescriptor:
-    """
-    A Mixin for RelatedObjectDescriptors which use current language in cache lookups.
-    """
-
-    accessor = None  # needs to be set on instance
-
-    def get_cache_name(self) -> str:
-        """
-        Used in django > 2.x
-        """
-        return build_localized_fieldname(self.accessor, get_language())  # type: ignore[arg-type]

modeltranslation/tests/test_utils.py

@@ -0,0 +1,15 @@
+from modeltranslation.utils import localized_cached_property, get_language
+from django.utils.translation import override
+
+
+def test_localized_cached_property():
+    class Foo:
+        @localized_cached_property
+        def bar(self):
+            return get_language()
+
+    instance = Foo()
+
+    for lang in ["en", "de"]:
+        with override(lang):
+            assert instance.bar == lang

modeltranslation/translator.py

@@ -21,7 +21,6 @@
 from modeltranslation import settings as mt_settings
 from modeltranslation.fields import (
     NONE,
-    LanguageCacheSingleObjectDescriptor,
     TranslatedManyToManyDescriptor,
     TranslatedRelationIdDescriptor,
     TranslationFieldDescriptor,
@@ -35,7 +34,12 @@
     rewrite_lookup_key,
 )
 from modeltranslation.thread_context import auto_populate_mode
-from modeltranslation.utils import build_localized_fieldname, parse_field
+from modeltranslation.utils import (
+    build_localized_fieldname,
+    parse_field,
+    localized_cached_property,
+    get_language,
+)
 
 # Re-export the decorator for convenience
 from modeltranslation.decorators import register
@@ -459,16 +463,21 @@ def patch_related_object_descriptor_caching(ro_descriptor):
     language-aware caching.
     """
 
-    class NewSingleObjectDescriptor(LanguageCacheSingleObjectDescriptor, ro_descriptor.__class__):
-        pass
-
-    ro_descriptor.related.get_cache_name = partial(
-        NewSingleObjectDescriptor.get_cache_name,
-        ro_descriptor,
-    )
-
-    ro_descriptor.accessor = ro_descriptor.related.get_accessor_name()
-    ro_descriptor.__class__ = NewSingleObjectDescriptor
+    class NewRelated(ro_descriptor.related.__class__):
+        def get_cache_name(self) -> str:
+            """
+            Used in django > 2.x
+            """
+            return self.cache_name
+
+        @localized_cached_property
+        def cache_name(self):
+            """
+            Used in django >= 5.1
+            """
+            return build_localized_fieldname(self.get_accessor_name(), get_language())
+
+    ro_descriptor.related.__class__ = NewRelated
 
 
 class Translator:

modeltranslation/utils.py

@@ -4,7 +4,7 @@
 from contextlib import contextmanager
 from typing import Any, TypeVar
 from collections.abc import Generator, Iterable, Iterator
-
+from functools import cached_property
 from django.db import models
 from django.utils.encoding import force_str
 from django.utils.functional import lazy
@@ -248,3 +248,15 @@ def lazy_register_model(old_model, new_model, translator):
     translator.lazy_operation(lazy_register_model, intermediary_model, klass)
 
     return klass
+
+
+class localized_cached_property(cached_property):
+    _attrname: str | None = None
+
+    @property
+    def attrname(self) -> str | None:
+        return self._attrname and "-".join((self._attrname, get_language()))
+
+    @attrname.setter
+    def attrname(self, value: str | None):
+        self._attrname = value