core[patch],community[patch]: Move file chat history back to community (#20834)

Marking as patch since we haven't had releases in between. This just reverting part of a PR from yesterday.

libs/core/langchain_core/chat_history.py

@@ -16,9 +16,7 @@
 """  # noqa: E501
 from __future__ import annotations
 
-import json
 from abc import ABC, abstractmethod
-from pathlib import Path
 from typing import List, Sequence, Union
 
 from langchain_core.messages import (
@@ -26,8 +24,6 @@ from langchain_core.messages import (
     BaseMessage,
     HumanMessage,
     get_buffer_string,
-    messages_from_dict,
-    messages_to_dict,
 )
 from langchain_core.pydantic_v1 import BaseModel, Field
 from langchain_core.runnables import run_in_executor
@@ -215,35 +211,3 @@ class InMemoryChatMessageHistory(BaseChatMessageHistory, BaseModel):
 
     async def aclear(self) -> None:
         self.clear()
-
-
-class FileChatMessageHistory(BaseChatMessageHistory):
-    """Chat message history that stores history in a local file."""
-
-    def __init__(self, file_path: str) -> None:
-        """Initialize the file path for the chat history.
-
-        Args:
-            file_path: The path to the local file to store the chat history.
-        """
-        self.file_path = Path(file_path)
-        if not self.file_path.exists():
-            self.file_path.touch()
-            self.file_path.write_text(json.dumps([]))
-
-    @property
-    def messages(self) -> List[BaseMessage]:  # type: ignore
-        """Retrieve the messages from the local file"""
-        items = json.loads(self.file_path.read_text())
-        messages = messages_from_dict(items)
-        return messages
-
-    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))
-
-    def clear(self) -> None:
-        """Clear session memory from the local file"""
-        self.file_path.write_text(json.dumps([]))

libs/core/tests/unit_tests/chat_history/test_file_chat_message_history.py

@@ -1,71 +0,0 @@
-import tempfile
-from pathlib import Path
-from typing import Generator
-
-import pytest
-
-from langchain_core.chat_history import FileChatMessageHistory
-from langchain_core.messages import AIMessage, HumanMessage
-
-
-@pytest.fixture
-def file_chat_message_history() -> Generator[FileChatMessageHistory, None, None]:
-    with tempfile.TemporaryDirectory() as temp_dir:
-        file_path = Path(temp_dir) / "test_chat_history.json"
-        file_chat_message_history = FileChatMessageHistory(str(file_path))
-        yield file_chat_message_history
-
-
-def test_add_messages(file_chat_message_history: FileChatMessageHistory) -> None:
-    file_chat_message_history.add_user_message("Hello!")
-    file_chat_message_history.add_ai_message("Hi there!")
-
-    messages = file_chat_message_history.messages
-    assert len(messages) == 2
-    assert isinstance(messages[0], HumanMessage)
-    assert isinstance(messages[1], AIMessage)
-    assert messages[0].content == "Hello!"
-    assert messages[1].content == "Hi there!"
-
-
-def test_clear_messages(file_chat_message_history: FileChatMessageHistory) -> None:
-    file_chat_message_history.add_user_message("Hello!")
-    file_chat_message_history.add_ai_message("Hi there!")
-
-    file_chat_message_history.clear()
-    messages = file_chat_message_history.messages
-    assert len(messages) == 0
-
-
-def test_multiple_sessions(file_chat_message_history: FileChatMessageHistory) -> None:
-    # First session
-    file_chat_message_history.add_user_message("Hello, AI!")
-    file_chat_message_history.add_ai_message("Hello, how can I help you?")
-    file_chat_message_history.add_user_message("Tell me a joke.")
-    file_chat_message_history.add_ai_message(
-        "Why did the chicken cross the road? To get to the other side!"
-    )
-
-    # Ensure the messages are added correctly in the first session
-    messages = file_chat_message_history.messages
-    assert len(messages) == 4
-    assert messages[0].content == "Hello, AI!"
-    assert messages[1].content == "Hello, how can I help you?"
-    assert messages[2].content == "Tell me a joke."
-    expected_content = "Why did the chicken cross the road? To get to the other side!"
-    assert messages[3].content == expected_content
-
-    # Second session (reinitialize FileChatMessageHistory)
-    file_path = file_chat_message_history.file_path
-    second_session_chat_message_history = FileChatMessageHistory(
-        file_path=str(file_path)
-    )
-
-    # Ensure the history is maintained in the second session
-    messages = second_session_chat_message_history.messages
-    assert len(messages) == 4
-    assert messages[0].content == "Hello, AI!"
-    assert messages[1].content == "Hello, how can I help you?"
-    assert messages[2].content == "Tell me a joke."
-    expected_content = "Why did the chicken cross the road? To get to the other side!"
-    assert messages[3].content == expected_content