Source code for langchain_community.chat_message_histories.neo4j

from typing import List, Optional, Union

from langchain_core.chat_history import BaseChatMessageHistory
from langchain_core.messages import BaseMessage, messages_from_dict
from langchain_core.utils import get_from_dict_or_env

from langchain_community.graphs import Neo4jGraph

[docs]class Neo4jChatMessageHistory(BaseChatMessageHistory): """Chat message history stored in a Neo4j database."""
[docs] def __init__( self, session_id: Union[str, int], url: Optional[str] = None, username: Optional[str] = None, password: Optional[str] = None, database: str = "neo4j", node_label: str = "Session", window: int = 3, *, graph: Optional[Neo4jGraph] = None, ): try: import neo4j except ImportError: raise ImportError( "Could not import neo4j python package. " "Please install it with `pip install neo4j`." ) # Make sure session id is not null if not session_id: raise ValueError("Please ensure that the session_id parameter is provided") # Graph object takes precedent over env or input params if graph: self._driver = graph._driver self._database = graph._database else: # Handle if the credentials are environment variables url = get_from_dict_or_env({"url": url}, "url", "NEO4J_URI") username = get_from_dict_or_env( {"username": username}, "username", "NEO4J_USERNAME" ) password = get_from_dict_or_env( {"password": password}, "password", "NEO4J_PASSWORD" ) database = get_from_dict_or_env( {"database": database}, "database", "NEO4J_DATABASE", "neo4j" ) self._driver = neo4j.GraphDatabase.driver(url, auth=(username, password)) self._database = database # Verify connection try: self._driver.verify_connectivity() except neo4j.exceptions.ServiceUnavailable: raise ValueError( "Could not connect to Neo4j database. " "Please ensure that the url is correct" ) except neo4j.exceptions.AuthError: raise ValueError( "Could not connect to Neo4j database. " "Please ensure that the username and password are correct" ) self._session_id = session_id self._node_label = node_label self._window = window # Create session node self._driver.execute_query( f"MERGE (s:`{self._node_label}` {{id:$session_id}})", {"session_id": self._session_id}, ).summary
@property def messages(self) -> List[BaseMessage]: """Retrieve the messages from Neo4j""" query = ( f"MATCH (s:`{self._node_label}`)-[:LAST_MESSAGE]->(last_message) " "WHERE = $session_id MATCH p=(last_message)<-[:NEXT*0.." f"{self._window*2}]-() WITH p, length(p) AS length " "ORDER BY length DESC LIMIT 1 UNWIND reverse(nodes(p)) AS node " "RETURN {data:{content: node.content}, type:node.type} AS result" ) records, _, _ = self._driver.execute_query( query, {"session_id": self._session_id} ) messages = messages_from_dict([el["result"] for el in records]) return messages @messages.setter def messages(self, messages: List[BaseMessage]) -> None: raise NotImplementedError( "Direct assignment to 'messages' is not allowed." " Use the 'add_messages' instead." )
[docs] def add_message(self, message: BaseMessage) -> None: """Append the message to the record in Neo4j""" query = ( f"MATCH (s:`{self._node_label}`) WHERE = $session_id " "OPTIONAL MATCH (s)-[lm:LAST_MESSAGE]->(last_message) " "CREATE (s)-[:LAST_MESSAGE]->(new:Message) " "SET new += {type:$type, content:$content} " "WITH new, lm, last_message WHERE last_message IS NOT NULL " "CREATE (last_message)-[:NEXT]->(new) " "DELETE lm" ) self._driver.execute_query( query, { "type": message.type, "content": message.content, "session_id": self._session_id, }, ).summary
[docs] def clear(self) -> None: """Clear session memory from Neo4j""" query = ( f"MATCH (s:`{self._node_label}`)-[:LAST_MESSAGE]->(last_message) " "WHERE = $session_id MATCH p=(last_message)<-[:NEXT]-() " "WITH p, length(p) AS length ORDER BY length DESC LIMIT 1 " "UNWIND nodes(p) as node DETACH DELETE node;" ) self._driver.execute_query(query, {"session_id": self._session_id}).summary
def __del__(self) -> None: if self._driver: self._driver.close()