fastAPI(5)--响应模型 response model

灰太狼 2022-12-27 06:26 91阅读 0赞

可以`response_model`在任何*路径操作中*使用参数声明用于响应的模型：

*  `@app.get()`
 *  `@app.post()`
 *  `@app.put()`
 *  `@app.delete()`

#!/usr/bin/env python
    # encoding: utf-8
    
    from fastapi import FastAPI
    from pydantic import BaseModel
    from typing import Optional, List
    import uvicorn
    
    app = FastAPI()
    
    class Item(BaseModel):
        name: str
        desc: Optional[str] = None
        price: float
        tax: Optional[float] = None
        tags: List[str] = []
    
    @app.get('/items/', response_model=Item)
    async def create_item(item: Item):
        return item
    
    if __name__ == '__main__':
        uvicorn.run(app= app, host='127.0.0.1', port=8000)

注意，`response_model`是“装饰”方法的参数（`get`，`post`等）。不像所有参数和主体一样，具有*路径操作功能*。

FastAPI将使用它`response_model`来：

*  将输出数据转换为其类型声明。
 *  验证数据。
 *  在OpenAPI *path操作中*，为响应添加一个JSON模式。
 *  将由自动文档系统使用。

但最重要的是：

*  将输出数据限制为模型的数据。我们将在下面看到其重要性。

2. 输入输出模型

#!/usr/bin/env python
    # encoding: utf-8
    
    from fastapi import FastAPI
    from pydantic import BaseModel, EmailStr
    from typing import Optional
    import uvicorn
    
    app = FastAPI()
    
    class UserIn(BaseModel):
        username: str
        password: str
        email: EmailStr
        full_name: Optional[str] = None
    
    class UserOut(BaseModel):
        username: str
        email: EmailStr
        full_name: Optional[str] = None
    
    
    @app.get('/items/', response_model=UserOut)
    async def create_item(*, user: UserIn):
        return user
    
    if __name__ == '__main__':
        uvicorn.run(app= app, host='127.0.0.1', port=8000)

EmailStr 安装方式： pip install pydantic\[email\]

如上所示，虽然路径操作函数返回的结果是user(包含了password)，但我们声明的Response模型是UserOut(不包含password)。

FastAPI会过滤掉所有不在输出模型中的数据，因此最终的输出结果里并没有password

运行后结果：

{
      "username": "string",
      "email": "user@example.com",
      "full_name": "string"
    }

3. 响应模型参数

#!/usr/bin/env python
    # encoding: utf-8
    
    import uvicorn
    from typing import List
    
    from fastapi import FastAPI
    from pydantic import BaseModel
    
    app = FastAPI()
    
    
    class Item(BaseModel):
        name: str
        description: str = None
        price: float
        tax: float = 10.5
        tags: List[str] = []
    
    
    items = {
        "foo": {"name": "Foo", "price": 50.2},
        "bar": {"name": "Bar", "description": "The bartenders", "price": 62, "tax": 20.2},
        "baz": {"name": "Baz", "description": None, "price": 50.2, "tax": 10.5, "tags": []},
    }
    
    # response_model_exclude_unset=True 默认值将不包括在响应中，仅包含实际设置的值
    @app.get("/items/{item_id}", response_model=Item, response_model_exclude_unset=True)
    async def read_item(item_id: str):
        return items[item_id]
    
    # response_model_exclude 排除‘tax’
    @app.get('/items/{item_id}/public', response_model=Item, response_model_exclude={'tax'})
    async def read_item_public_data(item_id: str):
        return items[item_id]
    
    # response_model_include 为只返回这个list里的参数
    @app.get(
        "/items/{item_id}/name",
        response_model=Item,
        response_model_include={"name", "description", 'tax'},
    )
    async def read_item_name(item_id: str):
        return items[item_id]
    
    if __name__ == '__main__':
        uvicorn.run(app= app, host='127.0.0.1', port=8000)

有时候只想返回被真正设置过的数据，而忽略其他未被设置过的或者缺省数据。可以用参数`response_model_exclude_unset来实现这个目的。`

# 访问：
    http://127.0.0.1:8000/items/foo
    # 返回结果：
    {
        "name": "Foo",
        "price": 50.2
    }
    # 访问：
    http://127.0.0.1:8000/items/bar/public
    # 返回结果：
    {
      "name": "Bar",
      "description": "The bartenders",
      "price": 62,
      "tags": []
    }
    # 访问：
    http://127.0.0.1:8000/items/foo/name
    # 返回结果：
    {
      "name": "Foo",
      "description": null,
      "tax": 10.5
    }

4. 列表模型

from typing import List
    from fastapi import FastAPI
    from pydantic import BaseModel
    
    app = FastAPI()
    
    
    class Item(BaseModel):
        name: str
        description: str
    
    
    items = [
        {"name": "Foo", "description": "There comes my hero"},
        {"name": "Red", "description": "It's my aeroplane"},
    ]
    
    
    @app.get("/items/", response_model=List[Item])
    async def read_items():
        return items

5. Response联合模型

from typing import Union
    from fastapi import FastAPI
    from pydantic import BaseModel
    
    app = FastAPI()
    
    class BaseItem(BaseModel):
        description: str
        type: str
    
    class CarItem(BaseItem):
        type = "car"
    
    class PlaneItem(BaseItem):
        type = "plane"
        size: int
    
    items = {
        "item1": {"description": "All my friends drive a low rider", "type": "car"},
        "item2": {
            "description": "Music is my aeroplane, it's my aeroplane",
            "type": "plane",
            "size": 5,
        },
    }
    
    @app.get("/items/{item_id}", response_model=Union[PlaneItem, CarItem])
    async def read_item(item_id: str):
        return items[item_id]

6. Response字典模型

from typing import Dict
    from fastapi import FastAPI
    
    app = FastAPI()
    
    
    @app.get("/keyword-weights/", response_model=Dict[str, float])
    async def read_keyword_weights():
        return {"foo": 2.3, "bar": 3.4}