安装

fastapi只支持Python3.6+ , 所以需要机器上的Python版本至少3.6+

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pip3 install fastapi
pip3 install uvicorn

创建应用

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from fastapi import FastAPI

app = FastAPI()

很简单，一行代码就成，和flask很像，同时很多初始话参数可以通过构造函数传入

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def __init__(
        self,
        *,
        debug: bool = False,
        routes: List[BaseRoute] = None,
        title: str = "FastAPI",
        description: str = "",
        version: str = "0.1.0",
        openapi_url: Optional[str] = "/openapi.json",
        openapi_tags: Optional[List[Dict[str, Any]]] = None,
        servers: Optional[List[Dict[str, Union[str, Any]]]] = None,
        default_response_class: Type[Response] = JSONResponse,
        docs_url: Optional[str] = "/docs",
        redoc_url: Optional[str] = "/redoc",
        swagger_ui_oauth2_redirect_url: Optional[str] = "/docs/oauth2-redirect",
        swagger_ui_init_oauth: Optional[dict] = None,
        middleware: Sequence[Middleware] = None,
        exception_handlers: Dict[Union[int, Type[Exception]], Callable] = None,
        on_startup: Sequence[Callable] = None,
        on_shutdown: Sequence[Callable] = None,
        openapi_prefix: str = "",
        root_path: str = "",
        **extra: Dict[str, Any],
    ) -> None:

支持这些参数，看名字就能很简单的知道这些参数具体的作用。

处理请求

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@app.get('/')
def user():
  return { 'app': user_id}

和flask一样，fastapi用装饰器处理请求，get,post这些分别对应HTTP的GET，POST方法，方法的参数表示请求的路径。

路径参数

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@app.get('/name')
async def get_user_name(user_id:int = Query(None)):
    return  {'user_id':user_id , 'user_name': 'tom'}

请求模型

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from fastapi import FastAPI, Query
from pydantic import BaseModel

class Item(BaseModel):
    name: str
    description: str = None
    price: float
    tax: float = None

app = FastAPI()

@app.post('/user/upload')
async def upload(* , item: Item):
    return item