FastAPI从入门到实战（18）——FastAPI 中间件、CORS、后台任务

中间件

@app.middleware('http')
async def add_process_time_header(request: Request, call_next):  # call_next将接收request请求做为参数
    start_time = time.time()
    response = await call_next(request)
    process_time = time.time() - start_time
    response.headers['X-Process-Time'] = str(process_time)  # 添加自定义的以“X-”开头的请求头
    return response

带yield的依赖的退出部分的代码 和 后台任务 会在中间件之后运行

CORS

from fastapi.middleware.cors import CORSMiddleware

app.add_middleware(
    CORSMiddleware,
    allow_origins=[
        "http://127.0.0.1",
        "http://127.0.0.1:8000"
    ],
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

后台任务

from fastapi import BackgroundTasks

def bg_task(framework: str):
    with open("README.md", mode="a") as f:
        f.write(f"## {framework} 框架精讲")


@app08.post("/background_tasks")
async def run_bg_task(framework: str, background_tasks: BackgroundTasks):
    """
    :param framework: 被调用的后台任务函数的参数
    :param background_tasks: FastAPI.BackgroundTasks
    :return:
    """
    background_tasks.add_task(bg_task, framework)
    return {"message": "任务已在后台运行"}