LangChain Chain

TIP

Chain 通过将多个组件串联或并联组合，实现复杂的 AI 工作流。

LCEL 表达式

python

from langchain_openai import ChatOpenAI
from langchain.prompts import ChatPromptTemplate
from langchain_core.output_parsers import StrOutputParser

llm = ChatOpenAI(model="gpt-4")
prompt = ChatPromptTemplate.from_template("解释{concept}")
parser = StrOutputParser()

chain = prompt | llm | parser
result = chain.invoke({"concept": "机器学习"})

RunnableParallel

python

from langchain_core.runnables import RunnableParallel

chain1 = prompt1 | llm
chain2 = prompt2 | llm

combined = RunnableParallel({
    "summary": chain1,
    "details": chain2,
})
result = combined.invoke({"topic": "深度学习"})

条件路由

python

from langchain_core.runnables import RunnableBranch

branch = RunnableBranch(
    (lambda x: x["lang"] == "python", python_chain),
    (lambda x: x["lang"] == "java", java_chain),
    default_chain
)