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LangChain 接入指南

LangChain 是一个用于构建 AI 应用的开发框架，支持多种 LLM 后端。

安装​

pip install langchain langchain-openai

配置 weelinking​

使用 ChatOpenAI​

from langchain_openai import ChatOpenAI

llm = ChatOpenAI(
    model="gpt-4o",
    openai_api_key="YOUR_API_KEY",
    openai_api_base="https://api.weelinking.com/v1",
    temperature=0.7
)

response = llm.invoke("你好，请介绍一下你自己")
print(response.content)

使用 OpenAI​

from langchain_openai import OpenAI

llm = OpenAI(
    model="gpt-3.5-turbo-instruct",
    openai_api_key="YOUR_API_KEY",
    openai_api_base="https://api.weelinking.com/v1"
)

response = llm.invoke("写一首关于春天的诗")
print(response)

高级用法​

对话链​

from langchain_openai import ChatOpenAI
from langchain.chains import ConversationChain
from langchain.memory import ConversationBufferMemory

llm = ChatOpenAI(
    model="gpt-4o",
    openai_api_key="YOUR_API_KEY",
    openai_api_base="https://api.weelinking.com/v1"
)

conversation = ConversationChain(
    llm=llm,
    memory=ConversationBufferMemory()
)

response1 = conversation.predict(input="你好！")
response2 = conversation.predict(input="我们刚才说了什么？")

RAG 应用​

from langchain_openai import ChatOpenAI, OpenAIEmbeddings
from langchain.vectorstores import FAISS
from langchain.chains import RetrievalQA
from langchain.document_loaders import TextLoader

# 配置 LLM
llm = ChatOpenAI(
    model="gpt-4o",
    openai_api_key="YOUR_API_KEY",
    openai_api_base="https://api.weelinking.com/v1"
)

# 配置 Embeddings
embeddings = OpenAIEmbeddings(
    openai_api_key="YOUR_API_KEY",
    openai_api_base="https://api.weelinking.com/v1"
)

# 加载文档
loader = TextLoader("document.txt")
documents = loader.load()

# 创建向量存储
vectorstore = FAISS.from_documents(documents, embeddings)

# 创建问答链
qa_chain = RetrievalQA.from_chain_type(
    llm=llm,
    chain_type="stuff",
    retriever=vectorstore.as_retriever()
)

response = qa_chain.run("文档中提到了什么？")

工具使用​

from langchain_openai import ChatOpenAI
from langchain.agents import initialize_agent, Tool
from langchain.agents import AgentType

llm = ChatOpenAI(
    model="gpt-4o",
    openai_api_key="YOUR_API_KEY",
    openai_api_base="https://api.weelinking.com/v1"
)

tools = [
    Tool(
        name="Calculator",
        func=lambda x: eval(x),
        description="用于数学计算"
    )
]

agent = initialize_agent(
    tools,
    llm,
    agent=AgentType.ZERO_SHOT_REACT_DESCRIPTION,
    verbose=True
)

agent.run("计算 25 * 4 + 10")

推荐模型​

场景模型
通用对话gpt-4o
复杂推理claude-3-opus, gpt-5
长文本gemini-2.5-pro
代码生成claude-sonnet-4-5

常见问题​

ImportError​

确保安装了正确的包：

pip install langchain-openai

API 连接失败​

检查 openai_api_base 参数格式，确保包含 /v1。