LangChain入门

背景

将qwen3作为LLM

Who are you

defmain():history={'messages':[]}whileTrue:q=input("你说: ")hm=HumanMessage(q)history['messages'].append(hm)print("AI:")history=agent.invoke(history)last_message=history['messages'][-1]ifisinstance(last_message,AIMessage):print(last_message.content)model=init_chat_model(model=config.model_name,api_key=config.api_key,base_url=config.base_url,model_provider='openai')agent=create_agent(model=model)if__name__=="__main__":main()

History & Session

defmain():whileTrue:q=input("你说: ")hm=HumanMessage(q)history={'messages':[hm]}print("AI:")# thread id算是session的唯一标识。langchain会帮我们记住historyresp=agent.invoke(history,{"configurable":{"thread_id":"1"}})print(resp["messages"][-1].content)model=init_chat_model(model=config.model_name,api_key=config.api_key,base_url=config.base_url,model_provider='openai')agent=create_agent(model=model,checkpointer=InMemorySaver())if__name__=="__main__":main()

流式输出

defmain():whileTrue:q=input("你说: ")hm=HumanMessage(q)history={'messages':[hm]}print("AI:",end='',flush=True)fortoken,messagesinagent.stream(history,config=RunnableConfig(configurable={'thread_id':'aaa'}),stream_mode='messages'):ifisinstance(token,AIMessageChunk):print(token.content,end='',flush=True)print()model=init_chat_model(model=config.model_name,api_key=config.api_key,base_url=config.base_url,model_provider='openai')withSqliteSaver.from_conn_string('checkpoints.db3')ascheckpointer:checkpointer.setup()agent=create_agent(model=model,middleware=[SummarizationMiddleware(model=model,trigger=("tokens",1000),keep=("messages",20))],checkpointer=checkpointer)if__name__=="__main__":main()