表单模型¶

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English version

你可以在 FastAPI 中使用 Pydantic 模型声明表单字段。

信息

要使用表单，首先安装 python-multipart。

确保你创建一个虚拟环境，激活它，然后再安装，例如：

$ pip install python-multipart

注意

自 FastAPI 版本 0.113.0 起支持此功能。🤓

表单的 Pydantic 模型¶

你只需声明一个 Pydantic 模型，其中包含你希望接收的表单字段，然后将参数声明为 Form：

Python 3.9+

from typing import Annotated

from fastapi import FastAPI, Form
from pydantic import BaseModel

app = FastAPI()


class FormData(BaseModel):
    username: str
    password: str


@app.post("/login/")
async def login(data: Annotated[FormData, Form()]):
    return data

🤓 Other versions and variants

Python 3.10+Python 3.10+ - non-AnnotatedPython 3.9+ - non-Annotated

from typing import Annotated

from fastapi import FastAPI, Form
from pydantic import BaseModel

app = FastAPI()


class FormData(BaseModel):
    username: str
    password: str


@app.post("/login/")
async def login(data: Annotated[FormData, Form()]):
    return data

Tip

Prefer to use the Annotated version if possible.

from fastapi import FastAPI, Form
from pydantic import BaseModel

app = FastAPI()


class FormData(BaseModel):
    username: str
    password: str


@app.post("/login/")
async def login(data: FormData = Form()):
    return data

Tip

Prefer to use the Annotated version if possible.

from fastapi import FastAPI, Form
from pydantic import BaseModel

app = FastAPI()


class FormData(BaseModel):
    username: str
    password: str


@app.post("/login/")
async def login(data: FormData = Form()):
    return data

FastAPI 将从请求中的表单数据中提取出每个字段的数据，并提供你定义的 Pydantic 模型。

检查文档¶

你可以在文档 UI 中验证它，地址为 /docs：

禁止额外的表单字段¶

在某些特殊使用情况下（可能并不常见），你可能希望将表单字段限制为仅在 Pydantic 模型中声明过的字段，并禁止任何额外的字段。

注意

自 FastAPI 版本 0.114.0 起支持此功能。🤓

你可以使用 Pydantic 的模型配置来 forbid 任何 extra 字段：

Python 3.9+

from typing import Annotated

from fastapi import FastAPI, Form
from pydantic import BaseModel

app = FastAPI()


class FormData(BaseModel):
    username: str
    password: str
    model_config = {"extra": "forbid"}


@app.post("/login/")
async def login(data: Annotated[FormData, Form()]):
    return data

🤓 Other versions and variants

Python 3.10+Python 3.10+ - non-AnnotatedPython 3.9+ - non-Annotated

from typing import Annotated

from fastapi import FastAPI, Form
from pydantic import BaseModel

app = FastAPI()


class FormData(BaseModel):
    username: str
    password: str
    model_config = {"extra": "forbid"}


@app.post("/login/")
async def login(data: Annotated[FormData, Form()]):
    return data

Tip

Prefer to use the Annotated version if possible.

from fastapi import FastAPI, Form
from pydantic import BaseModel

app = FastAPI()


class FormData(BaseModel):
    username: str
    password: str
    model_config = {"extra": "forbid"}


@app.post("/login/")
async def login(data: FormData = Form()):
    return data

Tip

Prefer to use the Annotated version if possible.

from fastapi import FastAPI, Form
from pydantic import BaseModel

app = FastAPI()


class FormData(BaseModel):
    username: str
    password: str
    model_config = {"extra": "forbid"}


@app.post("/login/")
async def login(data: FormData = Form()):
    return data

如果客户端尝试发送一些额外的数据，他们将收到错误响应。

例如，客户端尝试发送如下表单字段：

username: Rick
password: Portal Gun
extra: Mr. Poopybutthole

他们将收到一条错误响应，表明字段 extra 不被允许：

{
    "detail": [
        {
            "type": "extra_forbidden",
            "loc": ["body", "extra"],
            "msg": "Extra inputs are not permitted",
            "input": "Mr. Poopybutthole"
        }
    ]
}

总结¶

你可以使用 Pydantic 模型在 FastAPI 中声明表单字段。😎