FastAPI 响应模型

使用response_model参数，即可在以下路径参数中声明响应模型：

• @app.get()
• @app.put()
• @app.post()
• @app.delete()

from typing import List, Optional
from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()

class Item(BaseModel):
    name: str
    description: Optional[str] = None
    price: float
    tax: Optional[float] = None
    tags: List[str] = []
    
@app.post("/items/", response_model=Item)
async def create_item(item: Item):
    return item

注意：response_model是装饰器方法的参数，与之前的参数和请求体不同，他不是路径操作函数的参数。

response_model接收的类型与声明Pydantic模型属性的类型相同，可以是Pydantic模型，也可以是Pydantic模型列表，例如：List[Item]

返回相同的输入数据

from typing import Optional
from fastapi import FastAPI
from pydantic import BaseModel, EmailStr

app = FastAPI()

class UserIn(BaseModel):
    username: str
    password: str
    email: EmilStr
    full_name: Optional[str] = None
    
    
@app.post("/user/", response_model=UserIn)
async def create_user(user: UserIn):
    return user

使用此模型声明输入对象，并使用同一个模型声明输出对象：

from typing import Optional

from fastapi import FastAPI
from pydantic import BaseModel, EmailStr

app = FastAPI()


class UserIn(BaseModel):
    username: str
    password: str
    email: EmailStr
    full_name: Optional[str] = None


# Don't do this in production!
@app.post("/user/", response_model=UserIn)
async def create_user(user: UserIn):
    return user

现在，只要在浏览器中使用密码创建用户，API就会在响应中国返回相同的密码。本例中，因为是用户本人发送密码，这种操作没什么问题，但是如果在其他路径操作中使用同一个模型，就会把用户的密码发送给每一个客户端。

添加输出模型

相对于包含明文密码的输入模型，创建不含明文密码的输出模型：

from typing import Optional

from fastapi import FastAPI
from pydantic import BaseModel, EmailStr

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.post("/user/", response_model=UserOut)
async def create_user(user: UserIn):
    return user

这样，即便路径操作函数返回同样的输入用户：

from typing import Optional

from fastapi import FastAPI
from pydantic import BaseModel, EmailStr

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.post("/user/", response_model=UserOut)
async def create_user(user: UserIn):
    return user

但因为response_model中声明的UserOut模型没有包含密码：

from typing import Optional

from fastapi import FastAPI
from pydantic import BaseModel, EmailStr

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.post("/user/", response_model=UserOut)
async def create_user(user: UserIn):
    return user

FastAPI会过滤掉所有未在输出模型中声明的数据。

响应模型编码参数

响应模型支持默认值：

from typing import List, Optional

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: Optional[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": []},
}


@app.get("/items/{item_id}", response_model=Item, response_model_exclude_unset=True)
async def read_item(item_id: str):
    return items[item_id]

• description: Optional[str] = None 的默认值是 None
• tax: float = 10.5 的默认值是 10.5
• tags: List[str] = [] 的默认值是空列表： []

但如果没有为含默认值的属性另赋新值，输出结果会省略含默认值的属性。

例如，NoSQL 数据库的模型中往往包含很多可选属性，如果输出含默认值的属性，输出的 JSON 响应会特别长，此时，可以省略只含默认值的属性。

 

标签：FastAPI,模型,响应,user,str,BaseModel,import,Optional,app
来源： https://www.cnblogs.com/litianming/p/16225540.html