LangChain 1.0.3使用create_retrieval_chain替代RetrievalQA时导入失败求助

LangChain 1.0+版本对模块结构进行了调整，create_retrieval_chain和create_stuff_documents_chain的导入路径已变更，原文档中的旧导入路径不再适用。

修正后的导入代码 #

将原导入语句替换为以下内容：

from langchain.chains.retrieval import create_retrieval_chain
from langchain.chains.combine_documents.stuff import create_stuff_documents_chain
from langchain_core.prompts import ChatPromptTemplate
from langchain_openai import ChatOpenAI

完整可运行代码示例 #

from langchain.chains.retrieval import create_retrieval_chain
from langchain.chains.combine_documents.stuff import create_stuff_documents_chain
from langchain_core.prompts import ChatPromptTemplate
from langchain_openai import ChatOpenAI

retriever = ...  # 你的检索器实例
llm = ChatOpenAI()

system_prompt = (
    "Use the given context to answer the question. "
    "If you don't know the answer, say you don't know. "
    "Use three sentence maximum and keep the answer concise. "
    "Context: {context}"
)
prompt = ChatPromptTemplate.from_messages(
    [
        ("system", system_prompt),
        ("human", "{input}"),
    ]
)
question_answer_chain = create_stuff_documents_chain(llm, prompt)
chain = create_retrieval_chain(retriever, question_answer_chain)

# 替换为你的查询语句
query = "你的问题内容"
result = chain.invoke({"input": query})
print(result)

额外排查步骤 #

• 确认已安装完整的LangChain包，执行pip install langchain --upgrade确保版本为1.0.3或更高
• 避免仅安装langchain-core等子集包，完整包包含所有链实现模块

内容的提问来源于stack exchange，提问作者Saad Cherkaoui Ikbal