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如何在运行时传递回调

先决条件

本指南假设您熟悉以下概念

在许多情况下,在运行对象时传递处理程序更有优势。当我们在执行运行时使用 callbacks 关键字参数传递 CallbackHandlers 时,这些回调将由执行中涉及的所有嵌套对象发出。例如,当一个处理程序被传递给一个代理时,它将用于所有与代理相关的回调以及所有参与代理执行的对象,在本例中为工具和 LLM。

这可以防止我们必须手动将处理程序附加到每个单独的嵌套对象。这是一个示例

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.invoke({"number": "2"}, config={"callbacks": callbacks})
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_01D8Tt5FdtBk5gLTfBPm2tac', 'model': 'claude-3-sonnet-20240229', 'stop_reason': 'end_turn', 'stop_sequence': None, 'usage': {'input_tokens': 16, 'output_tokens': 13}}, id='run-bb0dddd8-85f3-4e6b-8553-eaa79f859ef8-0'))]] llm_output={'id': 'msg_01D8Tt5FdtBk5gLTfBPm2tac', '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_01D8Tt5FdtBk5gLTfBPm2tac', 'model': 'claude-3-sonnet-20240229', 'stop_reason': 'end_turn', 'stop_sequence': None, 'usage': {'input_tokens': 16, 'output_tokens': 13}} id='run-bb0dddd8-85f3-4e6b-8553-eaa79f859ef8-0'
AIMessage(content='1 + 2 = 3', response_metadata={'id': 'msg_01D8Tt5FdtBk5gLTfBPm2tac', 'model': 'claude-3-sonnet-20240229', 'stop_reason': 'end_turn', 'stop_sequence': None, 'usage': {'input_tokens': 16, 'output_tokens': 13}}, id='run-bb0dddd8-85f3-4e6b-8553-eaa79f859ef8-0')

如果模块已有关联的回调,这些回调将在运行时传递的任何回调之外运行。

下一步

您现在已经学习了如何在运行时传递回调。

接下来,查看本节中的其他操作指南,例如如何将回调传递到模块构造函数


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