Add support for GenericForeignKey and GenericRelation.

Author: WaVEV

.github/workflows/test-python.yml

@@ -83,6 +83,7 @@ jobs:
           defer
           defer_regress
           from_db_value
+          generic_relations
           introspection
           known_related_objects
           lookup

django_mongodb/features.py

@@ -79,6 +79,7 @@ class DatabaseFeatures(BaseDatabaseFeatures):
         "many_to_one.tests.ManyToOneTests.test_selects",
         # Incorrect JOIN with GenericRelation gives incorrect results.
         "aggregation_regress.tests.AggregationTests.test_aggregation_with_generic_reverse_relation",
+        "generic_relations.tests.GenericRelationsTests.test_queries_content_type_restriction",
         # subclasses of BaseDatabaseWrapper may require an is_usable() method
         "backends.tests.BackendTestCase.test_is_usable_after_database_disconnects",
         # Connection creation doesn't follow the usual Django API.
@@ -247,6 +248,7 @@ def django_test_expected_failures(self):
         },
         "Test assumes integer primary key.": {
             "db_functions.comparison.test_cast.CastTests.test_cast_to_integer_foreign_key",
+            "generic_relations.tests.GenericRelationsTests.test_cache_invalidation_for_content_type_id",
             "model_fields.test_foreignkey.ForeignKeyTests.test_to_python",
             "queries.test_qs_combinators.QuerySetSetOperationTests.test_order_raises_on_non_selected_column",
         },

django_mongodb/fields/__init__.py

@@ -1,8 +1,9 @@
 from .auto import ObjectIdAutoField
 from .duration import register_duration_field
 from .json import register_json_field
+from .object_id import ObjectIdField
 
-__all__ = ["register_fields", "ObjectIdAutoField"]
+__all__ = ["register_fields", "ObjectIdAutoField", "ObjectIdField"]
 
 
 def register_fields():

django_mongodb/fields/object_id.py

@@ -0,0 +1,30 @@
+from bson import ObjectId, errors
+from django.db.models.fields import Field
+from django.utils.translation import gettext_lazy as _
+
+
+class ObjectIdField(Field):
+    description = _("Object Id")
+
+    def get_internal_type(self):
+        return "ObjectIdField"
+
+    def db_type(self, connection):
+        return "ObjectId"
+
+    def get_prep_value(self, value):
+        value = super().get_prep_value(value)
+        return self.to_python(value)
+
+    def to_python(self, value):
+        if value is None:
+            return value
+        if isinstance(value, ObjectId | int):
+            return value
+        try:
+            return ObjectId(value)
+        except errors.InvalidId as e:
+            # A manually assigned integer ID?
+            if isinstance(value, str) and value.isdigit():
+                return int(value)
+            raise ValueError(f"Field '{self.name}' expected an ObjectId but got {value!r}.") from e