PYTHON-5488 - MongoClient.append_metadata should not add duplicates

pymongo/asynchronous/mongo_client.py

@@ -1043,6 +1043,7 @@ async def target() -> bool:
 
     def append_metadata(self, driver_info: DriverInfo) -> None:
         """Appends the given metadata to existing driver metadata.
+        If given driver_info.name is already present in the metadata, no append is done.
 
         :param driver_info: a :class:`~pymongo.driver_info.DriverInfo`
 
@@ -1053,7 +1054,11 @@ def append_metadata(self, driver_info: DriverInfo) -> None:
             raise TypeError(
                 f"driver_info must be an instance of DriverInfo, not {type(driver_info)}"
             )
-        self._options.pool_options._update_metadata(driver_info)
+        if (
+            driver_info.name
+            and driver_info.name not in self._options.pool_options.metadata["driver"]["name"]
+        ):
+            self._options.pool_options._update_metadata(driver_info)
 
     def _should_pin_cursor(self, session: Optional[AsyncClientSession]) -> Optional[bool]:
         return self._options.load_balanced and not (session and session.in_transaction)

pymongo/synchronous/mongo_client.py

@@ -1043,6 +1043,7 @@ def target() -> bool:
 
     def append_metadata(self, driver_info: DriverInfo) -> None:
         """Appends the given metadata to existing driver metadata.
+        If given driver_info.name is already present in the metadata, no append is done.
 
         :param driver_info: a :class:`~pymongo.driver_info.DriverInfo`
 
@@ -1053,7 +1054,11 @@ def append_metadata(self, driver_info: DriverInfo) -> None:
             raise TypeError(
                 f"driver_info must be an instance of DriverInfo, not {type(driver_info)}"
             )
-        self._options.pool_options._update_metadata(driver_info)
+        if (
+            driver_info.name
+            and driver_info.name not in self._options.pool_options.metadata["driver"]["name"]
+        ):
+            self._options.pool_options._update_metadata(driver_info)
 
     def _should_pin_cursor(self, session: Optional[ClientSession]) -> Optional[bool]:
         return self._options.load_balanced and not (session and session.in_transaction)

test/asynchronous/test_client_metadata.py

@@ -96,6 +96,7 @@ async def check_metadata_added(
         add_name: str,
         add_version: Optional[str],
         add_platform: Optional[str],
+        is_duplicate: bool = False,
     ) -> None:
         # send initial metadata
         name, version, platform, metadata = await self.send_ping_and_get_metadata(client, True)
@@ -107,15 +108,22 @@ async def check_metadata_added(
         new_name, new_version, new_platform, new_metadata = await self.send_ping_and_get_metadata(
             client, True
         )
-        self.assertEqual(new_name, f"{name}|{add_name}" if add_name is not None else name)
-        self.assertEqual(
-            new_version,
-            f"{version}|{add_version}" if add_version is not None else version,
-        )
-        self.assertEqual(
-            new_platform,
-            f"{platform}|{add_platform}" if add_platform is not None else platform,
-        )
+
+        if not is_duplicate:
+            self.assertEqual(new_name, f"{name}|{add_name}" if add_name is not None else name)
+            self.assertEqual(
+                new_version,
+                f"{version}|{add_version}" if add_version is not None else version,
+            )
+            self.assertEqual(
+                new_platform,
+                f"{platform}|{add_platform}" if add_platform is not None else platform,
+            )
+        # Metadata should be unchanged if the new name was already present
+        else:
+            self.assertEqual(new_name, name)
+            self.assertEqual(new_version, version)
+            self.assertEqual(new_platform, platform)
 
         metadata.pop("driver")
         metadata.pop("platform")
@@ -210,6 +218,16 @@ async def test_doesnt_update_established_connections(self):
         self.assertIsNone(self.handshake_req)
         self.assertEqual(listener.event_count(ConnectionClosedEvent), 0)
 
+    async def test_append_metadata_duplicate_name(self):
+        client = await self.async_rs_or_single_client(
+            "mongodb://" + self.server.address_string,
+            maxIdleTimeMS=1,
+            driver=DriverInfo("library", "1.2", "Library Platform"),
+        )
+        await self.check_metadata_added(
+            client, "library", "2.0", "Framework Platform", is_duplicate=True
+        )
+
 
 if __name__ == "__main__":
     unittest.main()

test/test_client_metadata.py

@@ -96,6 +96,7 @@ def check_metadata_added(
         add_name: str,
         add_version: Optional[str],
         add_platform: Optional[str],
+        is_duplicate: bool = False,
     ) -> None:
         # send initial metadata
         name, version, platform, metadata = self.send_ping_and_get_metadata(client, True)
@@ -107,15 +108,22 @@ def check_metadata_added(
         new_name, new_version, new_platform, new_metadata = self.send_ping_and_get_metadata(
             client, True
         )
-        self.assertEqual(new_name, f"{name}|{add_name}" if add_name is not None else name)
-        self.assertEqual(
-            new_version,
-            f"{version}|{add_version}" if add_version is not None else version,
-        )
-        self.assertEqual(
-            new_platform,
-            f"{platform}|{add_platform}" if add_platform is not None else platform,
-        )
+
+        if not is_duplicate:
+            self.assertEqual(new_name, f"{name}|{add_name}" if add_name is not None else name)
+            self.assertEqual(
+                new_version,
+                f"{version}|{add_version}" if add_version is not None else version,
+            )
+            self.assertEqual(
+                new_platform,
+                f"{platform}|{add_platform}" if add_platform is not None else platform,
+            )
+        # Metadata should be unchanged if the new name was already present
+        else:
+            self.assertEqual(new_name, name)
+            self.assertEqual(new_version, version)
+            self.assertEqual(new_platform, platform)
 
         metadata.pop("driver")
         metadata.pop("platform")
@@ -210,6 +218,14 @@ def test_doesnt_update_established_connections(self):
         self.assertIsNone(self.handshake_req)
         self.assertEqual(listener.event_count(ConnectionClosedEvent), 0)
 
+    def test_append_metadata_duplicate_name(self):
+        client = self.rs_or_single_client(
+            "mongodb://" + self.server.address_string,
+            maxIdleTimeMS=1,
+            driver=DriverInfo("library", "1.2", "Library Platform"),
+        )
+        self.check_metadata_added(client, "library", "2.0", "Framework Platform", is_duplicate=True)
+
 
 if __name__ == "__main__":
     unittest.main()