FastApi快速入门 05: 中间键、子应用

7.中间件

"中间件"是一个函数,它在每个请求被特定的路径操作处理之前,以及在每个响应返回之前工作。

要创建中间件你可以在函数的顶部使用装饰器 @app.middleware("http").

中间件参数接收如下参数:

• request

• 一个函数 call_next 它将接收 request 作为参数

  
  
  • 这个函数将 request 传递给相应的 路径操作
  • 然后它将返回由相应的路径操作生成的 response

• 然后你可以在返回 response 前进一步修改它

import time

from fastapi import FastAPI, Request

app = FastAPI()



@app.middleware("http")

async def add_process_time_header(request: Request, call_next):

    start_time = time.time()

    response = await call_next(request)

    process_time = time.time() - start_time
    response.headers["X-Process-Time"] = str(process_time)

    return response 

8.Background Tasks

background tasks 就是在返回响应之后立即运行的任务。

from fastapi import BackgroundTasks, FastAPI


app = FastAPI()


def write_notification(email: str, message=""):
    with open("log.txt", mode="w") as email_file:
        content = f"notification for {email}: {message}"
        email_file.write(content)


@app.post("/send-notification/{email}")
async def send_notification(email: str, background_tasks: BackgroundTasks):
    background_tasks.add_task(write_notification, email, message="some notification")
    return {"message": "Notification sent in the background"} 

9.子应用

如果你有2个独立的FastAPI的应用，你可以设置一个为主应用，另外一个为子应用：

from fastapi import FastAPI


app = FastAPI()




@app.get("/app")

def read_main():
    return {"message": "Hello World from main app"}



subapi = FastAPI()


@subapi.get("/sub")
def read_sub():
    return {"message": "Hello World from sub API"}


app.mount("/subapi", subapi)