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迁移出ConversationBufferMemory或ConversationStringBufferMemory

ConversationBufferMemoryConversationStringBufferMemory 被用来跟踪人类和AI助手之间的对话,而不进行任何额外的处理。

note

ConversationStringBufferMemory 等同于 ConversationBufferMemory,但针对的是非聊天模型的LLMs。

使用现有的现代原语处理对话历史的方法有:

  1. 使用LangGraph持久化并适当处理消息历史记录
  2. 使用LCEL与RunnableWithMessageHistory结合,并对消息历史进行适当的处理。

大多数用户会发现LangGraph持久化比等效的LCEL更易于使用和配置,特别是对于更复杂的用例。

设置

%%capture --no-stderr
%pip install --upgrade --quiet langchain-openai langchain
import os
from getpass import getpass

if "OPENAI_API_KEY" not in os.environ:
os.environ["OPENAI_API_KEY"] = getpass()

与LLMChain / ConversationChain的使用

本节展示了如何迁移与LLMChainConversationChain一起使用的ConversationBufferMemoryConversationStringBufferMemory

遗留

以下是ConversationBufferMemoryLLMChain或等效的ConversationChain的示例用法。

Details
from langchain.chains import LLMChain
from langchain.memory import ConversationBufferMemory
from langchain_core.messages import SystemMessage
from langchain_core.prompts import ChatPromptTemplate
from langchain_core.prompts.chat import (
ChatPromptTemplate,
HumanMessagePromptTemplate,
MessagesPlaceholder,
)
from langchain_openai import ChatOpenAI

prompt = ChatPromptTemplate(
[
MessagesPlaceholder(variable_name="chat_history"),
HumanMessagePromptTemplate.from_template("{text}"),
]
)

memory = ConversationBufferMemory(memory_key="chat_history", return_messages=True)

legacy_chain = LLMChain(
llm=ChatOpenAI(),
prompt=prompt,
memory=memory,
)

legacy_result = legacy_chain.invoke({"text": "my name is bob"})
print(legacy_result)

legacy_result = legacy_chain.invoke({"text": "what was my name"})
{'text': 'Hello Bob! How can I assist you today?', 'chat_history': [HumanMessage(content='my name is bob', additional_kwargs={}, response_metadata={}), AIMessage(content='Hello Bob! How can I assist you today?', additional_kwargs={}, response_metadata={})]}
legacy_result["text"]
'Your name is Bob. How can I assist you today, Bob?'
note

请注意,单个内存对象中不支持分离对话线程

LangGraph

下面的示例展示了如何使用LangGraph来实现带有ConversationBufferMemoryConversationChainLLMChain

此示例假设您已经对LangGraph有一定的了解。如果您还不熟悉,请参阅LangGraph快速入门指南以获取更多详细信息。

LangGraph 提供了许多额外的功能(例如,时间旅行和中断),并且适用于其他更复杂(和现实)的架构。

Details
import uuid

from IPython.display import Image, display
from langchain_core.messages import HumanMessage
from langgraph.checkpoint.memory import MemorySaver
from langgraph.graph import START, MessagesState, StateGraph

# Define a new graph
workflow = StateGraph(state_schema=MessagesState)

# Define a chat model
model = ChatOpenAI()


# Define the function that calls the model
def call_model(state: MessagesState):
response = model.invoke(state["messages"])
# We return a list, because this will get added to the existing list
return {"messages": response}


# Define the two nodes we will cycle between
workflow.add_edge(START, "model")
workflow.add_node("model", call_model)


# Adding memory is straight forward in langgraph!
memory = MemorySaver()

app = workflow.compile(
checkpointer=memory
)


# The thread id is a unique key that identifies
# this particular conversation.
# We'll just generate a random uuid here.
# This enables a single application to manage conversations among multiple users.
thread_id = uuid.uuid4()
config = {"configurable": {"thread_id": thread_id}}


input_message = HumanMessage(content="hi! I'm bob")
for event in app.stream({"messages": [input_message]}, config, stream_mode="values"):
event["messages"][-1].pretty_print()

# Here, let's confirm that the AI remembers our name!
input_message = HumanMessage(content="what was my name?")
for event in app.stream({"messages": [input_message]}, config, stream_mode="values"):
event["messages"][-1].pretty_print()
================================ Human Message =================================

hi! I'm bob
================================== Ai Message ==================================

Hello Bob! How can I assist you today?
================================ Human Message =================================

what was my name?
================================== Ai Message ==================================

Your name is Bob. How can I help you today, Bob?

LCEL 可运行的消息历史

或者,如果你有一个简单的链,你可以将链的聊天模型包装在RunnableWithMessageHistory中。

请参考以下迁移指南以获取更多信息。

使用预构建的代理

此示例展示了如何使用通过create_tool_calling_agent函数构建的预构建代理来使用代理执行器。

如果您正在使用其中一个旧的LangChain预构建代理,您应该能够将该代码替换为新的langgraph预构建代理,该代理利用了聊天模型的原生工具调用功能,并且可能会更好地开箱即用。

遗留用法

Details
from langchain import hub
from langchain.agents import AgentExecutor, create_tool_calling_agent
from langchain.memory import ConversationBufferMemory
from langchain_core.tools import tool
from langchain_openai import ChatOpenAI

model = ChatOpenAI(temperature=0)


@tool
def get_user_age(name: str) -> str:
"""Use this tool to find the user's age."""
# This is a placeholder for the actual implementation
if "bob" in name.lower():
return "42 years old"
return "41 years old"


tools = [get_user_age]

prompt = ChatPromptTemplate.from_messages(
[
("placeholder", "{chat_history}"),
("human", "{input}"),
("placeholder", "{agent_scratchpad}"),
]
)

# Construct the Tools agent
agent = create_tool_calling_agent(model, tools, prompt)
# Instantiate memory
memory = ConversationBufferMemory(memory_key="chat_history", return_messages=True)

# Create an agent
agent = create_tool_calling_agent(model, tools, prompt)
agent_executor = AgentExecutor(
agent=agent,
tools=tools,
memory=memory, # Pass the memory to the executor
)

# Verify that the agent can use tools
print(agent_executor.invoke({"input": "hi! my name is bob what is my age?"}))
print()
# Verify that the agent has access to conversation history.
# The agent should be able to answer that the user's name is bob.
print(agent_executor.invoke({"input": "do you remember my name?"}))
{'input': 'hi! my name is bob what is my age?', 'chat_history': [HumanMessage(content='hi! my name is bob what is my age?', additional_kwargs={}, response_metadata={}), AIMessage(content='Bob, you are 42 years old.', additional_kwargs={}, response_metadata={})], 'output': 'Bob, you are 42 years old.'}

{'input': 'do you remember my name?', 'chat_history': [HumanMessage(content='hi! my name is bob what is my age?', additional_kwargs={}, response_metadata={}), AIMessage(content='Bob, you are 42 years old.', additional_kwargs={}, response_metadata={}), HumanMessage(content='do you remember my name?', additional_kwargs={}, response_metadata={}), AIMessage(content='Yes, your name is Bob.', additional_kwargs={}, response_metadata={})], 'output': 'Yes, your name is Bob.'}

LangGraph

您可以按照标准的LangChain教程构建一个代理,深入了解其工作原理。

此示例在此明确显示,以便用户更容易比较旧版实现与相应的langgraph实现。

这个例子展示了如何在langgraph中为预构建的react agent添加内存。

更多详情,请参阅langgraph中的如何为预构建的ReAct代理添加内存指南。

Details
import uuid

from langchain_core.messages import HumanMessage
from langchain_core.tools import tool
from langchain_openai import ChatOpenAI
from langgraph.checkpoint.memory import MemorySaver
from langgraph.prebuilt import create_react_agent


@tool
def get_user_age(name: str) -> str:
"""Use this tool to find the user's age."""
# This is a placeholder for the actual implementation
if "bob" in name.lower():
return "42 years old"
return "41 years old"


memory = MemorySaver()
model = ChatOpenAI()
app = create_react_agent(
model,
tools=[get_user_age],
checkpointer=memory,
)

# The thread id is a unique key that identifies
# this particular conversation.
# We'll just generate a random uuid here.
# This enables a single application to manage conversations among multiple users.
thread_id = uuid.uuid4()
config = {"configurable": {"thread_id": thread_id}}

# Tell the AI that our name is Bob, and ask it to use a tool to confirm
# that it's capable of working like an agent.
input_message = HumanMessage(content="hi! I'm bob. What is my age?")

for event in app.stream({"messages": [input_message]}, config, stream_mode="values"):
event["messages"][-1].pretty_print()

# Confirm that the chat bot has access to previous conversation
# and can respond to the user saying that the user's name is Bob.
input_message = HumanMessage(content="do you remember my name?")

for event in app.stream({"messages": [input_message]}, config, stream_mode="values"):
event["messages"][-1].pretty_print()
================================ Human Message =================================

hi! I'm bob. What is my age?
================================== Ai Message ==================================
Tool Calls:
get_user_age (call_oEDwEbIDNdokwqhAV6Azn47c)
Call ID: call_oEDwEbIDNdokwqhAV6Azn47c
Args:
name: bob
================================= Tool Message =================================
Name: get_user_age

42 years old
================================== Ai Message ==================================

Bob, you are 42 years old! If you need any more assistance or information, feel free to ask.
================================ Human Message =================================

do you remember my name?
================================== Ai Message ==================================

Yes, your name is Bob. If you have any other questions or need assistance, feel free to ask!

如果我们使用不同的线程ID,它将开始一个新的对话,机器人将不知道我们的名字!

config = {"configurable": {"thread_id": "123456789"}}

input_message = HumanMessage(content="hi! do you remember my name?")

for event in app.stream({"messages": [input_message]}, config, stream_mode="values"):
event["messages"][-1].pretty_print()
================================ Human Message =================================

hi! do you remember my name?
================================== Ai Message ==================================

Hello! Yes, I remember your name. It's great to see you again! How can I assist you today?

下一步

探索LangGraph的持久性:

使用简单的LCEL添加持久性(对于更复杂的用例,推荐使用langgraph):

处理消息历史记录:


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