Source code for langchain_community.chat_message_histories.file
import json
from pathlib import Path
from typing import List, Optional
from langchain_core.chat_history import (
BaseChatMessageHistory,
)
from langchain_core.messages import BaseMessage, messages_from_dict, messages_to_dict
[docs]class FileChatMessageHistory(BaseChatMessageHistory):
"""Chat message history that stores history in a local file."""
[docs] def __init__(
self,
file_path: str,
*,
encoding: Optional[str] = None,
ensure_ascii: bool = True,
) -> None:
"""Initialize the file path for the chat history.
Args:
file_path: The path to the local file to store the chat history.
encoding: The encoding to use for file operations. Defaults to None.
ensure_ascii: If True, escape non-ASCII in JSON. Defaults to True.
"""
self.file_path = Path(file_path)
self.encoding = encoding
self.ensure_ascii = ensure_ascii
if not self.file_path.exists():
self.file_path.touch()
self.file_path.write_text(
json.dumps([], ensure_ascii=self.ensure_ascii), encoding=self.encoding
)
@property
def messages(self) -> List[BaseMessage]: # type: ignore
"""Retrieve the messages from the local file"""
items = json.loads(self.file_path.read_text(encoding=self.encoding))
messages = messages_from_dict(items)
return messages
[docs] def add_message(self, message: BaseMessage) -> None:
"""Append the message to the record in the local file"""
messages = messages_to_dict(self.messages)
messages.append(messages_to_dict([message])[0])
self.file_path.write_text(
json.dumps(messages, ensure_ascii=self.ensure_ascii), encoding=self.encoding
)
[docs] def clear(self) -> None:
"""Clear session memory from the local file"""
self.file_path.write_text(
json.dumps([], ensure_ascii=self.ensure_ascii), encoding=self.encoding
)