Expose database in Neo4jMessageHistory (#354)

* Expose database in Neo4jMessageHistory

* Remove unused import

Author: stellasia

src/neo4j_graphrag/message_history.py

@@ -148,8 +148,8 @@ class Neo4jMessageHistory(MessageHistory):
     Args:
         session_id (Union[str, int]): Unique identifier for the chat session.
         driver (neo4j.Driver): Neo4j driver instance.
-        node_label (str, optional): Label used for session nodes in Neo4j. Defaults to "Session".
         window (Optional[PositiveInt], optional): Number of previous messages to return when retrieving messages.
+        database (Optional[str], optional): Neo4j database name.
 
     """
 
@@ -158,28 +158,33 @@ def __init__(
         session_id: Union[str, int],
         driver: neo4j.Driver,
         window: Optional[PositiveInt] = None,
+        database: Optional[str] = None,
     ) -> None:
         validated_data = Neo4jMessageHistoryModel(
             session_id=session_id,
             driver_model=Neo4jDriverModel(driver=driver),
             window=window,
+            database=database,
         )
         self._driver = validated_data.driver_model.driver
         self._session_id = validated_data.session_id
         self._window = (
             "" if validated_data.window is None else validated_data.window - 1
         )
+        self._database = validated_data.database
         # Create session node
         self._driver.execute_query(
             query_=CREATE_SESSION_NODE_QUERY.format(node_label="Session"),
             parameters_={"session_id": self._session_id},
+            database_=self._database,
         )
 
     @property
     def messages(self) -> List[LLMMessage]:
         result = self._driver.execute_query(
             query_=GET_MESSAGES_QUERY.format(node_label="Session", window=self._window),
             parameters_={"session_id": self._session_id},
+            database_=self._database,
         )
         messages = [
             LLMMessage(
@@ -210,6 +215,7 @@ def add_message(self, message: LLMMessage) -> None:
                 "content": message["content"],
                 "session_id": self._session_id,
             },
+            database_=self._database,
         )
 
     def clear(self, delete_session_node: bool = False) -> None:
@@ -222,9 +228,11 @@ def clear(self, delete_session_node: bool = False) -> None:
             self._driver.execute_query(
                 query_=DELETE_SESSION_AND_MESSAGES_QUERY.format(node_label="Session"),
                 parameters_={"session_id": self._session_id},
+                database_=self._database,
             )
         else:
             self._driver.execute_query(
                 query_=DELETE_MESSAGES_QUERY.format(node_label="Session"),
                 parameters_={"session_id": self._session_id},
+                database_=self._database,
             )

src/neo4j_graphrag/types.py

@@ -302,6 +302,7 @@ class Neo4jMessageHistoryModel(BaseModel):
     session_id: Union[str, int]
     driver_model: Neo4jDriverModel
     window: Optional[PositiveInt] = None
+    database: Optional[str] = None
 
     @field_validator("session_id")
     def validate_session_id(cls, v: Union[str, int]) -> Union[str, int]:

tests/unit/test_message_history.py

@@ -95,3 +95,20 @@ def test_neo4j_message_history_messages_setter(driver: MagicMock) -> None:
         str(exc_info.value)
         == "Direct assignment to 'messages' is not allowed. Use the 'add_messages' instead."
     )
+
+
+def test_neo4j_message_history_messages_getter_custom_db(driver: MagicMock) -> None:
+    driver.execute_query.side_effect = [
+        MagicMock(records=[]),
+        MagicMock(
+            records=[{"result": {"data": {"content": "my message"}, "role": "user"}}]
+        ),
+    ]
+    message_history = Neo4jMessageHistory(
+        session_id="123", driver=driver, database="my_db"
+    )
+    messages = message_history.messages
+    assert len(messages) == 1
+    assert messages[0] == LLMMessage(content="my message", role="user")
+    for c in driver.execute_query.call_args_list:
+        assert c.kwargs["database_"] == "my_db"