PYTHON-5061 - Add an API to extend the bson TypeRegistry (#2345)

bson/codec_options.py

@@ -160,6 +160,16 @@ class TypeRegistry:
                     f"Expected an instance of {TypeEncoder.__name__}, {TypeDecoder.__name__}, or {TypeCodec.__name__}, got {codec!r} instead"
                 )
 
+    @property
+    def codecs(self) -> list[TypeEncoder | TypeDecoder | TypeCodec]:
+        """The list of type codecs in this registry."""
+        return self.__type_codecs
+
+    @property
+    def fallback_encoder(self) -> Optional[_Fallback]:
+        """The fallback encoder in this registry."""
+        return self._fallback_encoder
+
     def _validate_type_encoder(self, codec: _Codec) -> None:
         from bson import _BUILT_IN_TYPES
 

doc/changelog.rst

@@ -1,6 +1,13 @@
 Changelog
 =========
 
+Changes in Version 4.14.0 (XXXX/XX/XX)
+--------------------------------------
+PyMongo 4.14 brings a number of changes including:
+
+- Added :attr:`bson.codec_options.TypeRegistry.codecs` and :attr:`bson.codec_options.TypeRegistry.fallback_encoder` properties
+  to allow users to directly access the type codecs and fallback encoder for a given :class:`bson.codec_options.TypeRegistry`.
+
 Changes in Version 4.13.0 (2025/05/14)
 --------------------------------------
 

test/asynchronous/test_custom_types.py

@@ -579,6 +579,15 @@ class TestTypeRegistry(unittest.TestCase):
         with self.assertRaisesRegex(TypeError, err_msg):
             TypeRegistry(fallback_encoder="hello")  # type: ignore[arg-type]
 
+    def test_type_registry_codecs(self):
+        codec_instances = [codec() for codec in self.codecs]
+        type_registry = TypeRegistry(codec_instances)
+        self.assertEqual(type_registry.codecs, codec_instances)
+
+    def test_type_registry_fallback(self):
+        type_registry = TypeRegistry(fallback_encoder=self.fallback_encoder)
+        self.assertEqual(type_registry.fallback_encoder, self.fallback_encoder)
+
     def test_type_registry_repr(self):
         codec_instances = [codec() for codec in self.codecs]
         type_registry = TypeRegistry(codec_instances)

test/test_custom_types.py

@@ -579,6 +579,15 @@ class TestTypeRegistry(unittest.TestCase):
         with self.assertRaisesRegex(TypeError, err_msg):
             TypeRegistry(fallback_encoder="hello")  # type: ignore[arg-type]
 
+    def test_type_registry_codecs(self):
+        codec_instances = [codec() for codec in self.codecs]
+        type_registry = TypeRegistry(codec_instances)
+        self.assertEqual(type_registry.codecs, codec_instances)
+
+    def test_type_registry_fallback(self):
+        type_registry = TypeRegistry(fallback_encoder=self.fallback_encoder)
+        self.assertEqual(type_registry.fallback_encoder, self.fallback_encoder)
+
     def test_type_registry_repr(self):
         codec_instances = [codec() for codec in self.codecs]
         type_registry = TypeRegistry(codec_instances)