connection for multiple db in same cluster created duplicate MongoClient

docs/changelog.rst

@@ -8,6 +8,7 @@ Development
 ===========
 - (Fill this out as you fix issues and develop your features).
 - Fix for uuidRepresentation not read when provided in URI #2741
+- Fix connection for multiple db in same cluster created duplicate MongoClient #2768
 - Add option to user array_filters https://www.mongodb.com/docs/manual/reference/operator/update/positional-filtered/ #2769
 - Fix combination of __raw__ and mongoengine syntax #2773
 - Add tests against MongoDB 6.0 and MongoDB 7.0 in the pipeline
@@ -22,6 +23,7 @@ Development
 - Add `text_score` argument on :meth:`~mongoengine.Document.search_text()` to allow text_score computation to be turned off
     as it interfer with natural returned documents order #2759
 
+
 Changes in 0.27.0
 =================
 - Update uuidRepresentation warnings with "unspecified" as the future default (instead of 'standard' previously advertised) #2739

mongoengine/connection.py

@@ -399,7 +399,13 @@ def _clean_settings(settings_dict):
         # Only remove the name but it's important to
         # keep the username/password/authentication_source/authentication_mechanism
         # to identify if the connection could be shared (cfr https://github.com/MongoEngine/mongoengine/issues/2047)
-        return {k: v for k, v in settings_dict.items() if k != "name"}
+        _clean = {k: v for k, v in settings_dict.items() if k != "name"}
+
+        # In case of multiple db on the same cluster
+        _clean["host"] = [
+            i.replace(f'/{settings_dict["name"]}', "") for i in _clean["host"]
+        ]
+        return _clean
 
     cleaned_conn_settings = _clean_settings(connection_settings)
     for db_alias, connection_settings in connection_settings_bis:

tests/test_connection.py

@@ -132,6 +132,10 @@ class History2(Document):
         connect("db1", alias="db1")
         connect("db2", alias="db2")
 
+        conn1 = get_connection("db2")
+        conn2 = get_connection("db2")
+        assert conn1 == conn2
+
         History.drop_collection()
         History1.drop_collection()
         History2.drop_collection()
@@ -704,6 +708,21 @@ def test_connect_uri_uuidrepresentation_default_to_pythonlegacy(self):
         )
         disconnect(rand)
 
+    def test_connect_deduplication(self):
+        connect(host="mongodb://localhost:27017/mongoenginetest_1", alias="test_1")
+        connect(host="mongodb://localhost:27017/mongoenginetest_2", alias="test_2")
+
+        conn1 = get_connection("test_1")
+        conn2 = get_connection("test_2")
+        assert conn1 == conn2
+        assert isinstance(conn1, pymongo.mongo_client.MongoClient)
+
+        db1 = get_db("test_1")
+        db2 = get_db("test_2")
+        assert isinstance(db2, pymongo.database.Database)
+        assert db1.name == "mongoenginetest_1"
+        assert db2.name == "mongoenginetest_2"
+
 
 if __name__ == "__main__":
     unittest.main()