PYTHON-3283 Remove Generic Typing from the ClientSession Class (#952)

pymongo/client_session.py

@@ -140,7 +140,6 @@ from typing import (
     Any,
     Callable,
     ContextManager,
-    Generic,
     Mapping,
     NoReturn,
     Optional,
@@ -164,7 +163,6 @@ from pymongo.helpers import _RETRYABLE_ERROR_CODES
 from pymongo.read_concern import ReadConcern
 from pymongo.read_preferences import ReadPreference, _ServerMode
 from pymongo.server_type import SERVER_TYPE
-from pymongo.typings import _DocumentType
 from pymongo.write_concern import WriteConcern
 
 
@@ -461,7 +459,7 @@ if TYPE_CHECKING:
     from pymongo.mongo_client import MongoClient
 
 
-class ClientSession(Generic[_DocumentType]):
+class ClientSession:
     """A session for ordering sequential operations.
 
     :class:`ClientSession` instances are **not thread-safe or fork-safe**.
@@ -476,13 +474,13 @@ class ClientSession(Generic[_DocumentType]):
 
     def __init__(
         self,
-        client: "MongoClient[_DocumentType]",
+        client: "MongoClient",
         server_session: Any,
         options: SessionOptions,
         implicit: bool,
     ) -> None:
         # A MongoClient, a _ServerSession, a SessionOptions, and a set.
-        self._client: MongoClient[_DocumentType] = client
+        self._client: MongoClient = client
         self._server_session = server_session
         self._options = options
         self._cluster_time = None
@@ -515,14 +513,14 @@ class ClientSession(Generic[_DocumentType]):
         if self._server_session is None:
             raise InvalidOperation("Cannot use ended session")
 
-    def __enter__(self) -> "ClientSession[_DocumentType]":
+    def __enter__(self) -> "ClientSession":
         return self
 
     def __exit__(self, exc_type: Any, exc_val: Any, exc_tb: Any) -> None:
         self._end_session(lock=True)
 
     @property
-    def client(self) -> "MongoClient[_DocumentType]":
+    def client(self) -> "MongoClient":
         """The :class:`~pymongo.mongo_client.MongoClient` this session was
         created from.
         """

pymongo/mongo_client.py

@@ -1630,7 +1630,7 @@ class MongoClient(common.BaseObject, Generic[_DocumentType]):
         causal_consistency: Optional[bool] = None,
         default_transaction_options: Optional[client_session.TransactionOptions] = None,
         snapshot: Optional[bool] = False,
-    ) -> client_session.ClientSession[_DocumentType]:
+    ) -> client_session.ClientSession:
         """Start a logical session.
 
         This method takes the same parameters as
@@ -1681,7 +1681,7 @@ class MongoClient(common.BaseObject, Generic[_DocumentType]):
     @contextlib.contextmanager
     def _tmp_session(
         self, session: Optional[client_session.ClientSession], close: bool = True
-    ) -> "Generator[Optional[client_session.ClientSession[Any]], None, None]":
+    ) -> "Generator[Optional[client_session.ClientSession], None, None]":
         """If provided session is None, lend a temporary session."""
         if session is not None:
             if not isinstance(session, client_session.ClientSession):

test/test_mypy.py

@@ -43,6 +43,7 @@ from test.utils import rs_or_single_client
 from bson import CodecOptions, decode, decode_all, decode_file_iter, decode_iter, encode
 from bson.raw_bson import RawBSONDocument
 from bson.son import SON
+from pymongo import ASCENDING
 from pymongo.collection import Collection
 from pymongo.mongo_client import MongoClient
 from pymongo.operations import InsertOne
@@ -313,6 +314,14 @@ class TestDocumentType(unittest.TestCase):
     def test_son_document_type_runtime(self) -> None:
         client = MongoClient(document_class=SON[str, Any], connect=False)
 
+    @only_type_check
+    def test_create_index(self) -> None:
+        client: MongoClient[Dict[str, str]] = MongoClient("test")
+        db = client.test
+        with client.start_session() as session:
+            index = db.test.create_index([("user_id", ASCENDING)], unique=True, session=session)
+            assert isinstance(index, str)
+
 
 class TestCommandDocumentType(unittest.TestCase):
     @only_type_check