如何在 FastAPI 的同一应用程序中从不同的 API 调用 API？

Question

（我确实在 SO 上找到了以下问题，但它对我没有帮助： 是否可以让 api 调用另一个 api，让它们都在同一个应用程序中？ ）

我正在使用具有以下文件夹结构的 Fastapi 制作应用程序

main.py是应用程序的入口点

from fastapi import FastAPI
from fastapi.middleware.cors import CORSMiddleware

from app.api.v1 import lines, upload
from app.core.config import settings

app = FastAPI(
    title=settings.PROJECT_NAME,
    version=0.1,
    openapi_url=f'{settings.API_V1_STR}/openapi.json',
    root_path=settings.ROOT_PATH
)

app.add_middleware(
    CORSMiddleware,
    allow_origins=settings.BACKEND_CORS_ORIGINS,
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

app.include_router(upload.router, prefix=settings.API_V1_STR)
app.include_router(lines.router, prefix=settings.API_V1_STR)

在lines.py中，我有 2 个 GET 端点：

• /one-random-line --> 从.txt文件中返回随机行
• /one-random-line-backwards --> 应该返回/one-random-line的 output

由于第二个 GET 端点的 output 应该是第一个 GET 端点的 output 的反转字符串，因此我尝试执行此处提到的以下步骤

代码：

import random

from fastapi import APIRouter, Request
from starlette.responses import RedirectResponse

router = APIRouter(
    prefix="/get-info",
    tags=["Get Information"],
    responses={
        200: {'description': 'Success'},
        400: {'description': 'Bad Request'},
        403: {'description': 'Forbidden'},
        500: {'description': 'Internal Server Error'}
    }
)


@router.get('/one-random-line')
def get_one_random_line(request: Request):
    lines = open('netflix_list.txt').read().splitlines()
    if request.headers.get('accept') in ['application/json', 'application/xml']:
        random_line = random.choice(lines)
    else:
        random_line = 'This is an example'
    return {'line': random_line}


@router.get('/one-random-line-backwards')
def get_one_random_line_backwards():
    url = router.url_path_for('get_one_random_line')
    response = RedirectResponse(url=url)
    return {'message': response[::-1]}

当我这样做时，我收到以下错误：

TypeError: 'RedirectResponse' object is not subscriptable

当我将第二个 GET 端点的return更改为return {'message': response}时，我得到以下 output

我在做什么错误？

例子：

如果/one-random-line端点的 output 是 'Maverick'，那么/one-random-line-backwards的 output 应该是 'kcirevam'

Answer 1

重构您的代码以将公共部分作为您调用的 function - 您通常将其放在 controller 外部的模块中。

# this function could live as LineService.get_random_line for example
# its responsibility is to fetch a random line from a file
def get_random_line(path="netflix_list.txt"):
    lines = open(path).read().splitlines()
    return random.choice(lines)


# this function encodes the rule that "if the accepted response is json or xml
# we do the random value, otherwise we return a default value"
def get_random_or_default_line_for_accept_value(accept, path="netflix_list.txt", default_value="This is an example"):
    if accept not in ("application/json", "application/xml"):
        return default_value

    return get_random_line(path=path)


@router.get('/one-random-line')
def get_one_random_line(request: Request):
    return {
        "line": get_random_or_default_line_for_accept_value(
            accept=request.headers.get('accept'),
        ),
    }


@router.get('/one-random-line-backwards')
def get_one_random_line_backwards(request: Request):
    return {
        "line": get_random_or_default_line_for_accept_value(
            accept=request.headers.get('accept'),
        )[::-1],
    }

Answer 2

您可以直接从代码中调用任何端点作为 function 调用，您不必处理RedirectResponse()或任何东西。 下面是一个示例，说明它的外观并将按原样运行：

from fastapi import FastAPI, Request

app = FastAPI()


@app.get("/one-random-line")
async def get_one_random_line(request: Request):
    # implement your own logic here, this will only return a static line
    return {"line": "This is an example"}


@app.get("/one-random-line-backwards")
async def get_one_random_line_backwards(request: Request):
    # You don't have to do fancy http stuff, just call your endpoint:
    one_line = await get_one_random_line(request)
    return {"line": one_line["line"][::-1]}


if __name__ == "__main__":
    import uvicorn

    uvicorn.run(app, host="0.0.0.0", port=8000)

使用curl我们得到以下结果：

% curl localhost:8000/one-random-line          
{"line":"This is an example"}%     
% curl localhost:8000/one-random-line-backwards
{"line":"elpmaxe na si sihT"}%