Langchain/FastAPI 应用遇到 404 错误
我正在按照这个 langchain 的教程示例 进行学习。
为什么我会遇到404错误呢？这里的代码和示例完全一样，没有任何修改。在启动应用程序并访问“/agent”这个路径时，我收到了404错误。我在下面提供了代码和控制台输出。非常感谢任何帮助。
#!/usr/bin/env python
from typing import List
from fastapi import FastAPI
from langchain_core.prompts import ChatPromptTemplate
from langchain_openai import ChatOpenAI
from langchain_community.document_loaders import WebBaseLoader
from langchain_openai import OpenAIEmbeddings
from langchain_community.vectorstores import FAISS
from langchain_text_splitters import RecursiveCharacterTextSplitter
from langchain.tools.retriever import create_retriever_tool
from langchain_community.tools.tavily_search import TavilySearchResults
from langchain import hub
from langchain.agents import create_openai_functions_agent
from langchain.agents import AgentExecutor
from langchain.pydantic_v1 import BaseModel, Field
from langchain_core.messages import BaseMessage
from langserve import add_routes
# 1. Load Retriever
loader = WebBaseLoader("https://docs.smith.langchain.com/user_guide")
docs = loader.load()
text_splitter = RecursiveCharacterTextSplitter()
documents = text_splitter.split_documents(docs)
embeddings = OpenAIEmbeddings()
vector = FAISS.from_documents(documents, embeddings)
retriever = vector.as_retriever()
# 2. Create Tools
retriever_tool = create_retriever_tool(
retriever,
"langsmith_search",
"Search for information about LangSmith. For any questions about LangSmith, you must use this tool!",
)
search = TavilySearchResults()
tools = [retriever_tool, search]
# 3. Create Agent
prompt = hub.pull("hwchase17/openai-functions-agent")
llm = ChatOpenAI(model="gpt-3.5-turbo", temperature=0)
agent = create_openai_functions_agent(llm, tools, prompt)
agent_executor = AgentExecutor(agent=agent, tools=tools, verbose=True)
# 4. App definition
app = FastAPI(
title="LangChain Server",
version="1.0",
description="A simple API server using LangChain's Runnable interfaces",
)
# 5. Adding chain route
# We need to add these input/output schemas because the current AgentExecutor
# is lacking in schemas.
class Input(BaseModel):
input: str
chat_history: List[BaseMessage] = Field(
...,
extra={"widget": {"type": "chat", "input": "location"}},
)
class Output(BaseModel):
output: str
add_routes(
app,
agent_executor.with_types(input_type=Input, output_type=Output),
path="/agent",
)
if __name__ == "__main__":
import uvicorn
uvicorn.run(app, host="localhost", port=8000)
这是控制台输出：
INFO: Started server process [55250]
INFO: Waiting for application startup.
__ ___ .__ __. _______ _______. _______ .______ ____ ____ _______
| | / \ | \ | | / _____| / || ____|| _ \ \ \ / / | ____|
| | / ^ \ | \| | | | __ | (----`| |__ | |_) | \ \/ / | |__
| | / /_\ \ | . ` | | | |_ | \ \ | __| | / \ / | __|
| `----./ _____ \ | |\ | | |__| | .----) | | |____ | |\ \----. \ / | |____
|_______/__/ \__\ |__| \__| \______| |_______/ |_______|| _| `._____| \__/ |_______|
LANGSERVE: Playground for chain "/agent/" is live at:
LANGSERVE: │
LANGSERVE: └──> /agent/playground/
LANGSERVE:
LANGSERVE: See all available routes at /docs/
LANGSERVE: ⚠️ Using pydantic 2.6.4. OpenAPI docs for invoke, batch, stream, stream_log endpoints will not be generated. API endpoints and playground should work as expected. If you need to see the docs, you can downgrade to pydantic 1. For example, `pip install pydantic==1.10.13`. See https://github.com/tiangolo/fastapi/issues/10360 for details.
INFO: Application startup complete.
INFO: Uvicorn running on http://localhost:8000 (Press CTRL+C to quit)
INFO: ::1:58755 - "GET /agent HTTP/1.1" 404 Not Found
INFO: ::1:58756 - "GET /agent HTTP/1.1" 404 Not Found