如何将回调附加到可运行对象
Prerequisites
本指南假设您熟悉以下概念：
如果你正在组合一系列可运行对象，并希望在多次执行中重用回调函数，你可以使用.with_config()方法附加回调函数。这可以避免每次调用链时都需要传递回调函数。
important
with_config() 绑定一个配置，该配置将被解释为运行时配置。因此，这些回调将传播到所有子组件。
这是一个例子：
from typing import Any, Dict, List
from langchain_anthropic import ChatAnthropic
from langchain_core.callbacks import BaseCallbackHandler
from langchain_core.messages import BaseMessage
from langchain_core.outputs import LLMResult
from langchain_core.prompts import ChatPromptTemplate
class LoggingHandler(BaseCallbackHandler):
def on_chat_model_start(
self, serialized: Dict[str, Any], messages: List[List[BaseMessage]], **kwargs
) -> None:
print("Chat model started")
def on_llm_end(self, response: LLMResult, **kwargs) -> None:
print(f"Chat model ended, response: {response}")
def on_chain_start(
self, serialized: Dict[str, Any], inputs: Dict[str, Any], **kwargs
) -> None:
print(f"Chain {serialized.get('name')} started")
def on_chain_end(self, outputs: Dict[str, Any], **kwargs) -> None:
print(f"Chain ended, outputs: {outputs}")
callbacks = [LoggingHandler()]
llm = ChatAnthropic(model="claude-3-sonnet-20240229")
prompt = ChatPromptTemplate.from_template("What is 1 + {number}?")
chain = prompt | llm
chain_with_callbacks = chain.with_config(callbacks=callbacks)
chain_with_callbacks.invoke({"number": "2"})
Chain RunnableSequence started
Chain ChatPromptTemplate started
Chain ended, outputs: messages=[HumanMessage(content='What is 1 + 2?')]
Chat model started
Chat model ended, response: generations=[[ChatGeneration(text='1 + 2 = 3', message=AIMessage(content='1 + 2 = 3', response_metadata={'id': 'msg_01NTYMsH9YxkoWsiPYs4Lemn', 'model': 'claude-3-sonnet-20240229', 'stop_reason': 'end_turn', 'stop_sequence': None, 'usage': {'input_tokens': 16, 'output_tokens': 13}}, id='run-d6bcfd72-9c94-466d-bac0-f39e456ad6e3-0'))]] llm_output={'id': 'msg_01NTYMsH9YxkoWsiPYs4Lemn', 'model': 'claude-3-sonnet-20240229', 'stop_reason': 'end_turn', 'stop_sequence': None, 'usage': {'input_tokens': 16, 'output_tokens': 13}} run=None
Chain ended, outputs: content='1 + 2 = 3' response_metadata={'id': 'msg_01NTYMsH9YxkoWsiPYs4Lemn', 'model': 'claude-3-sonnet-20240229', 'stop_reason': 'end_turn', 'stop_sequence': None, 'usage': {'input_tokens': 16, 'output_tokens': 13}} id='run-d6bcfd72-9c94-466d-bac0-f39e456ad6e3-0'
AIMessage(content='1 + 2 = 3', response_metadata={'id': 'msg_01NTYMsH9YxkoWsiPYs4Lemn', 'model': 'claude-3-sonnet-20240229', 'stop_reason': 'end_turn', 'stop_sequence': None, 'usage': {'input_tokens': 16, 'output_tokens': 13}}, id='run-d6bcfd72-9c94-466d-bac0-f39e456ad6e3-0')
绑定的回调函数将针对所有嵌套模块运行。
下一步
你现在已经学会了如何将回调附加到一个链上。
接下来，查看本节中的其他操作指南，例如如何在运行时传递回调。