使用FastAPI的APIRouter路由子模块时遇参数错误问题求助

main.py中编写的FastAPI代码里，/test接口可正常访问，但在default.py通过APIRouter定义的/test2接口调用时抛出TypeError，提示test2() takes 0 positional arguments but 1 was given，根路由/可正常工作。

main.py代码 #

from fastapi import FastAPI, Request
from fastapi.responses import HTMLResponse
from fastapi.middleware.gzip import GZipMiddleware
from fastapi.templating import Jinja2Templates
from fastapi.staticfiles import StaticFiles
from my_app.web.views import default

app = FastAPI()
app.add_middleware(GZipMiddleware, minimum_size=500)
app.include_router(default.router)
#app.include_router(data_mgr_view.router)

app.mount("/static", StaticFiles(directory="static"), name="static")
app.mount("/templates", Jinja2Templates(directory="templates"), name="templates")


@app.get('/test')
async def test():
    return "test successful"

default.py代码 #

import sys, traceback
import pandas as pd
from fastapi import APIRouter, Request, Query
from my_app.web.models.response_data import ResponseData
from my_app.data.providers.internals_provider import MktInternalsProvider
from my_app.config import tmplts

router = APIRouter(prefix="")

@router.route('/')
async def root(request: Request):
    context = {"title":"Playground", "content":f"Place for my charts, studies, etc..."}
    return tmplts.TemplateResponse(request=request, name="index.html", context=context)

@router.route('/test2')
async def test2():
    return "test2 success"

报错栈 #

Traceback (most recent call last):
  File "/usr/local/lib/python3.11/site-packages/uvicorn/protocols/http/httptools_impl.py", line 411, in run_asgi
    result = await app(  # type: ignore[func-returns-value]
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/uvicorn/middleware/proxy_headers.py", line 69, in __call__
    return await self.app(scope, receive, send)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/fastapi/applications.py", line 1054, in __call__
    await super().__call__(scope, receive, send)
  File "/usr/local/lib/python3.11/site-packages/starlette/applications.py", line 123, in __call__
    await self.middleware_stack(scope, receive, send)
  File "/usr/local/lib/python3.11/site-packages/starlette/middleware/errors.py", line 186, in __call__
    raise exc
  File "/usr/local/lib/python3.11/site-packages/starlette/middleware/errors.py", line 164, in __call__
    await self.app(scope, receive, _send)
  File "/usr/local/lib/python3.11/site-packages/starlette/middleware/gzip.py", line 24, in __call__
    await responder(scope, receive, send)
  File "/usr/local/lib/python3.11/site-packages/starlette/middleware/gzip.py", line 44, in __call__
    await self.app(scope, receive, self.send_with_gzip)
  File "/usr/local/lib/python3.11/site-packages/starlette/middleware/exceptions.py", line 65, in __call__
    await wrap_app_handling_exceptions(self.app, conn)(scope, receive, send)
  File "/usr/local/lib/python3.11/site-packages/starlette/_exception_handler.py", line 64, in wrapped_app
    raise exc
  File "/usr/local/lib/python3.11/site-packages/starlette/_exception_handler.py", line 53, in wrapped_app
    await app(scope, receive, sender)
  File "/usr/local/lib/python3.11/site-packages/starlette/routing.py", line 756, in __call__
    await self.middleware_stack(scope, receive, send)
  File "/usr/local/lib/python3.11/site-packages/starlette/routing.py", line 776, in app
    await route.handle(scope, receive, send)
  File "/usr/local/lib/python3.11/site-packages/starlette/routing.py", line 297, in handle
    await self.app(scope, receive, send)
  File "/usr/local/lib/python3.11/site-packages/starlette/routing.py", line 77, in app
    await wrap_app_handling_exceptions(app, request)(scope, receive, send)
  File "/usr/local/lib/python3.11/site-packages/starlette/_exception_handler.py", line 64, in wrapped_app
    raise exc
  File "/usr/local/lib/python3.11/site-packages/starlette/_exception_handler.py", line 53, in wrapped_app
    await app(scope, receive, sender)
  File "/usr/local/lib/python3.11/site-packages/starlette/routing.py", line 72, in app
    response = await func(request)
                     ^^^^^^^^^^^^^
TypeError: test2() takes 0 positional arguments but 1 was given

原因 #

使用@router.route()装饰器时，FastAPI（底层基于Starlette）会自动向视图函数传递request对象，无论你是否需要该参数。而test2函数没有定义接收这个参数，因此触发TypeError。

解决方法二选一： #

1. 为test2添加request参数（即使不用）
   修改default.py中的test2函数：

@router.route('/test2')
async def test2(request: Request):
    return "test2 success"

2. 改用HTTP方法专用装饰器
   和main.py中的/test接口一样，使用@router.get()（或对应HTTP方法的装饰器，如post、put等），这种情况下如果不需要request，可不定义参数：

@router.get('/test2')
async def test2():
    return "test2 success"

内容的提问来源于stack exchange，提问作者mike01010