PYTHON-3821 use overload pattern for _DocumentType (#1352)

bson/__init__.py

@@ -1106,9 +1106,21 @@ def _decode_all(
     _decode_all = _cbson._decode_all  # noqa: F811
 
 
+@overload
+def decode_all(data: "_ReadableBuffer", codec_options: None = None) -> "List[Dict[str, Any]]":
+    ...
+
+
+@overload
 def decode_all(
-    data: "_ReadableBuffer", codec_options: "Optional[CodecOptions[_DocumentType]]" = None
+    data: "_ReadableBuffer", codec_options: "CodecOptions[_DocumentType]"
 ) -> "List[_DocumentType]":
+    ...
+
+
+def decode_all(
+    data: "_ReadableBuffer", codec_options: "Optional[CodecOptions[_DocumentType]]" = None
+) -> "Union[List[Dict[str, Any]], List[_DocumentType]]":
     """Decode BSON data to multiple documents.
 
     `data` must be a bytes-like object implementing the buffer protocol that
@@ -1131,11 +1143,13 @@ def decode_all(
        Replaced `as_class`, `tz_aware`, and `uuid_subtype` options with
        `codec_options`.
     """
-    opts = codec_options or DEFAULT_CODEC_OPTIONS
-    if not isinstance(opts, CodecOptions):
+    if codec_options is None:
+        return _decode_all(data, DEFAULT_CODEC_OPTIONS)
+
+    if not isinstance(codec_options, CodecOptions):
         raise _CODEC_OPTIONS_TYPE_ERROR
 
-    return _decode_all(data, opts)  # type:ignore[arg-type]
+    return _decode_all(data, codec_options)
 
 
 def _decode_selective(rawdoc: Any, fields: Any, codec_options: Any) -> Mapping[Any, Any]:
@@ -1242,9 +1256,21 @@ def _decode_all_selective(data: Any, codec_options: CodecOptions, fields: Any) -
     ]
 
 
+@overload
+def decode_iter(data: bytes, codec_options: None = None) -> "Iterator[Dict[str, Any]]":
+    ...
+
+
+@overload
 def decode_iter(
-    data: bytes, codec_options: "Optional[CodecOptions[_DocumentType]]" = None
+    data: bytes, codec_options: "CodecOptions[_DocumentType]"
 ) -> "Iterator[_DocumentType]":
+    ...
+
+
+def decode_iter(
+    data: bytes, codec_options: "Optional[CodecOptions[_DocumentType]]" = None
+) -> "Union[Iterator[Dict[str, Any]], Iterator[_DocumentType]]":
     """Decode BSON data to multiple documents as a generator.
 
     Works similarly to the decode_all function, but yields one document at a
@@ -1278,9 +1304,23 @@ def decode_iter(
         yield _bson_to_dict(elements, opts)
 
 
+@overload
 def decode_file_iter(
-    file_obj: Union[BinaryIO, IO], codec_options: "Optional[CodecOptions[_DocumentType]]" = None
+    file_obj: Union[BinaryIO, IO], codec_options: None = None
+) -> "Iterator[Dict[str, Any]]":
+    ...
+
+
+@overload
+def decode_file_iter(
+    file_obj: Union[BinaryIO, IO], codec_options: "CodecOptions[_DocumentType]"
 ) -> "Iterator[_DocumentType]":
+    ...
+
+
+def decode_file_iter(
+    file_obj: Union[BinaryIO, IO], codec_options: "Optional[CodecOptions[_DocumentType]]" = None
+) -> "Union[Iterator[Dict[str, Any]], Iterator[_DocumentType]]":
     """Decode bson data from a file to multiple documents as a generator.
 
     Works similarly to the decode_all function, but reads from the file object

pymongo/collection.py

@@ -427,24 +427,6 @@ def database(self) -> Database[_DocumentType]:
         """
         return self.__database
 
-    # @overload
-    # def with_options(
-    #     self,
-    #     codec_options: None = None,
-    #     read_preference: Optional[_ServerMode] = None,
-    #     write_concern: Optional[WriteConcern] = None,
-    #     read_concern: Optional[ReadConcern] = None,
-    # ) -> Collection[Dict[str, Any]]: ...
-
-    # @overload
-    # def with_options(
-    #     self,
-    #     codec_options: bson.CodecOptions[_DocumentType],
-    #     read_preference: Optional[_ServerMode] = None,
-    #     write_concern: Optional[WriteConcern] = None,
-    #     read_concern: Optional[ReadConcern] = None,
-    # ) -> Collection[_DocumentType]: ...
-
     def with_options(
         self,
         codec_options: Optional[bson.CodecOptions[_DocumentTypeArg]] = None,

test/test_typing.py

@@ -242,6 +242,11 @@ def foo(self):
         rt_document3 = decode(bsonbytes2, codec_options=codec_options2)
         assert rt_document3.raw
 
+    def test_bson_decode_no_codec_option(self) -> None:
+        doc = decode_all(encode({"a": 1}))
+        assert doc
+        doc[0]["a"] = 2
+
     def test_bson_decode_all(self) -> None:
         doc = {"_id": 1}
         bsonbytes = encode(doc)
@@ -266,6 +271,15 @@ def foo(self):
         rt_documents3 = decode_all(bsonbytes3, codec_options3)
         assert rt_documents3[0].raw
 
+    def test_bson_decode_all_no_codec_option(self) -> None:
+        docs = decode_all(b"")
+        docs.append({"new": 1})
+
+        docs = decode_all(encode({"a": 1}))
+        assert docs
+        docs[0]["a"] = 2
+        docs.append({"new": 1})
+
     def test_bson_decode_iter(self) -> None:
         doc = {"_id": 1}
         bsonbytes = encode(doc)
@@ -290,6 +304,11 @@ def foo(self):
         rt_documents3 = decode_iter(bsonbytes3, codec_options3)
         assert next(rt_documents3).raw
 
+    def test_bson_decode_iter_no_codec_option(self) -> None:
+        doc = next(decode_iter(encode({"a": 1})))
+        assert doc
+        doc["a"] = 2
+
     def make_tempfile(self, content: bytes) -> Any:
         fileobj = tempfile.TemporaryFile()
         fileobj.write(content)
@@ -324,6 +343,12 @@ def foo(self):
         rt_documents3 = decode_file_iter(fileobj3, codec_options3)
         assert next(rt_documents3).raw
 
+    def test_bson_decode_file_iter_none_codec_option(self) -> None:
+        fileobj = self.make_tempfile(encode({"new": 1}))
+        doc = next(decode_file_iter(fileobj))
+        assert doc
+        doc["a"] = 2
+
 
 class TestDocumentType(unittest.TestCase):
     @only_type_check