Python LangChain 开发问题：ImportError: Unable to import langchain_anthropic.

fromlangchain.agentsimportcreate_agentdefget_weather(city:str)->str:"""获取指定城市的天气"""returnf"{city}天气总是晴朗！"agent=create_agent(model="anthropic:claude-sonnet-4-5",tools=[get_weather],system_prompt="你是一个乐于助人的助手",)# 执行代理agent.invoke({"messages":[{"role":"user","content":"旧金山天气如何？"}]})

• 在 Python 开发中，使用 LangChain 时，执行上述代码时，出现如下错误信息

D:\PythonCode\LangChainTest\.venv\Scripts\python.exe D:\PythonCode\LangChainTest\main.py D:\PythonCode\LangChainTest\.venv\Lib\site-packages\langchain_core\_api\deprecation.py:26: UserWarning: Core Pydantic V1 functionality isn't compatible with Python 3.14 or greater. from pydantic.v1.fields import FieldInfo as FieldInfoV1 Traceback (most recent call last): File "D:\PythonCode\LangChainTest\main.py", line 7, in <module> agent = create_agent( model="anthropic:claude-sonnet-4-5", tools=[get_weather], system_prompt="你是一个乐于助人的助手", ) File "D:\PythonCode\LangChainTest\.venv\Lib\site-packages\langchain\agents\factory.py", line 686, in create_agent model = init_chat_model(model) File "D:\PythonCode\LangChainTest\.venv\Lib\site-packages\langchain\chat_models\base.py", line 316, in init_chat_model return _init_chat_model_helper( cast("str", model), model_provider=model_provider, **kwargs, ) File "D:\PythonCode\LangChainTest\.venv\Lib\site-packages\langchain\chat_models\base.py", line 345, in _init_chat_model_helper _check_pkg("langchain_anthropic") ~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^ File "D:\PythonCode\LangChainTest\.venv\Lib\site-packages\langchain\chat_models\base.py", line 533, in _check_pkg raise ImportError(msg) ImportError: Unable to import langchain_anthropic. Please install with `pip install -U langchain-anthropic` Process finished with exit code 1

问题原因

• 这个错误信息表示 LangChain 需要相应的模型包来调用 Anthropic 模型

处理策略

• 安装必要的模型包

pipinstalllangchain-anthropic