FastAPI Response(四) 高級定制的Response

作者：麥克煎蛋   出處：https://www.cnblogs.com/mazhiyong/ 轉載請保留這段聲明，謝謝！

 

我們可以更靈活的定制返回結果。(這部分是相對高級的內容，如果你是初次接觸FastAPI那么可以忽略)

參數responses

我們可以傳遞給路徑操作裝飾器一個參數responses，他接收一個字典數據，鍵值是不同的HTTP狀態碼，內容是不同情況下的返回內容(字典格式)。

如果返回內容包含鍵值model，那么它的作用與response_model相同，指向的內容是Pydantic模型。

 

如下示例，當返回狀態碼是404的時候，對應的Pydantic模型是Message：

from fastapi import FastAPI
from fastapi.responses import JSONResponse
from pydantic import BaseModel


class Item(BaseModel):
    id: str
    value: str


class Message(BaseModel):
    message: str


app = FastAPI()


@app.get("/items/{item_id}", response_model=Item, responses={404: {"model": Message}})
async def read_item(item_id: str):
    if item_id == "foo":
        return {"id": "foo", "value": "there goes my hero"}
    else:
        return JSONResponse(status_code=404, content={"message": "Item not found"})

在上面的示例中，正常情況下返回的數據模型是Item，404的時候返回的數據模型是Message。

不同的media type

參數responses也支持不同的media type。

from typing import Optional

from fastapi import FastAPI
from fastapi.responses import FileResponse
from pydantic import BaseModel


class Item(BaseModel):
    id: str
    value: str


app = FastAPI()


@app.get(
    "/items/{item_id}",
    response_model=Item,
    responses={ 200: { "content": {"image/png": {}}, "description": "Return the JSON item or an image.", } },
)
async def read_item(item_id: str, img: Optional[bool] = None):
    if img:
        return FileResponse("image.png", media_type="image/png")
    else:
        return {"id": "foo", "value": "there goes my hero"}

如上所示，默認的media type是application/json，同時還支持image/png。

返回信息的組合格式

我們可以合並不同的組合信息，其中可以包含response_model, status_code, 以及 responses等參數。

from fastapi import FastAPI
from fastapi.responses import JSONResponse
from pydantic import BaseModel


class Item(BaseModel):
    id: str
    value: str


class Message(BaseModel):
    message: str


app = FastAPI()


@app.get(
    "/items/{item_id}",
    response_model=Item,
 responses={ 404: {"model": Message, "description": "The item was not found"}, 200: { "description": "Item requested by ID", "content": { "application/json": { "example": {"id": "bar", "value": "The bar tenders"} } }, }, },
)
async def read_item(item_id: str):
    if item_id == "foo":
        return {"id": "foo", "value": "there goes my hero"}
    else:
        return JSONResponse(status_code=404, content={"message": "Item not found"})

合並預定義responses與自定義responses

from typing import Optional

from fastapi import FastAPI
from fastapi.responses import FileResponse
from pydantic import BaseModel


class Item(BaseModel):
    id: str
    value: str


responses = { 404: {"description": "Item not found"}, 302: {"description": "The item was moved"}, 403: {"description": "Not enough privileges"}, }


app = FastAPI()


@app.get(
    "/items/{item_id}",
    response_model=Item,
    responses={**responses, 200: {"content": {"image/png": {}}}},
)
async def read_item(item_id: str, img: Optional[bool] = None):
    if img:
        return FileResponse("image.png", media_type="image/png")
    else:
        return {"id": "foo", "value": "there goes my hero"}