feat: Support F and Concat expressions in annotate()

Refs #735

modeltranslation/manager.py

@@ -15,13 +15,15 @@ from django.contrib.admin.utils import get_model_from_relation
 from django.core.exceptions import FieldDoesNotExist
 from django.db import models
 from django.db.backends.utils import CursorWrapper
-from django.db.models import Field, Model
+from django.db.models import Field, Model, F
 from django.db.models.expressions import Col
+from django.db.models.functions import Concat, ConcatPair
 from django.db.models.lookups import Lookup
 from django.db.models.query import QuerySet, ValuesIterable
 from django.db.models.utils import create_namedtuple_class
 from django.utils.tree import Node
 
+from modeltranslation._typing import Self, AutoPopulate
 from modeltranslation.fields import TranslationField
 from modeltranslation.thread_context import auto_populate_mode
 from modeltranslation.utils import (
@@ -30,7 +32,6 @@ from modeltranslation.utils import (
     get_language,
     resolution_order,
 )
-from modeltranslation._typing import Self, AutoPopulate
 
 _C2F_CACHE: dict[tuple[type[Model], str], Field] = {}
 _F2TM_CACHE: dict[type[Model], dict[str, type[Model]]] = {}
@@ -513,6 +514,27 @@ class MultilingualQuerySet(QuerySet[_T]):
         new_key = rewrite_lookup_key(self.model, field_name)
         return super().dates(new_key, *args, **kwargs)
 
+    def _rewrite_concat(self, concat: Concat | ConcatPair):
+        new_source_expressions = []
+        for exp in concat.source_expressions:
+            if isinstance(exp, (Concat, ConcatPair)):
+                exp = self._rewrite_concat(exp)
+            if isinstance(exp, F):
+                exp = self._rewrite_f(exp)
+            new_source_expressions.append(exp)
+        concat.set_source_expressions(new_source_expressions)
+        return concat
+
+    def annotate(self, *args: Any, **kwargs: Any) -> Self:
+        if not self._rewrite:
+            return super().annotate(*args, **kwargs)
+        for key, val in list(kwargs.items()):
+            if isinstance(val, models.F):
+                kwargs[key] = self._rewrite_f(val)
+            if isinstance(val, Concat):
+                kwargs[key] = self._rewrite_concat(val)
+        return super().annotate(*args, **kwargs)
+
 
 class FallbackValuesIterable(ValuesIterable):
     queryset: MultilingualQuerySet[Model]

modeltranslation/tests/tests.py

@@ -18,7 +18,7 @@ from django.core.management import call_command
 from django.core.management.base import CommandError
 from django.db import IntegrityError
 from django.db.models import CharField, Count, F, Q, TextField, Value
-from django.db.models.functions import Cast
+from django.db.models.functions import Cast, Concat
 from django.test import TestCase, TransactionTestCase
 from django.test.utils import override_settings
 from django.utils.translation import get_language, override, trans_real
@@ -3670,6 +3670,45 @@ class TestManager(ModeltranslationTestBase):
             assert titles_for_en == (("title_1_en", "desc_1_en"), ("title_2_en", "desc_1_en"))
             assert titles_for_de == (("title_1_de", "desc_1_de"), ("title_2_de", "desc_1_de"))
 
+    def test_annotate(self):
+        """Test if annotating is language-aware."""
+        test = models.TestModel.objects.create(title_en="title_en", title_de="title_de")
+
+        assert "en" == get_language()
+        assert (
+            models.TestModel.objects.annotate(custom_title=F("title")).values_list(
+                "custom_title", flat=True
+            )[0]
+            == "title_en"
+        )
+        with override("de"):
+            assert (
+                models.TestModel.objects.annotate(custom_title=F("title")).values_list(
+                    "custom_title", flat=True
+                )[0]
+                == "title_de"
+            )
+            assert (
+                models.TestModel.objects.annotate(
+                    custom_title=Concat(F("title"), Value("value1"), Value("value2"))
+                ).values_list("custom_title", flat=True)[0]
+                == "title_devalue1value2"
+            )
+            assert (
+                models.TestModel.objects.annotate(
+                    custom_title=Concat(F("title"), Concat(F("title"), Value("value")))
+                ).values_list("custom_title", flat=True)[0]
+                == "title_detitle_devalue"
+            )
+        models.ForeignKeyModel.objects.create(test=test)
+        models.ForeignKeyModel.objects.create(test=test)
+        assert (
+            models.TestModel.objects.annotate(Count("test_fks")).values_list(
+                "test_fks__count", flat=True
+            )[0]
+            == 2
+        )
+
 
 class TranslationModelFormTest(ModeltranslationTestBase):
     def test_fields(self):