如何在FastAPI中使用带有表单数据的PYDANIC模型？ [英] How to use a Pydantic model with Form data in FastAPI?

问题描述

我正在尝试从HTML表单提交数据，并使用PYDANIC模型对其进行验证。

使用此代码

from fastapi import FastAPI, Form
from pydantic import BaseModel
from starlette.responses import HTMLResponse


app = FastAPI()

@app.get("/form", response_class=HTMLResponse)
def form_get():
    return '''<form method="post"> 
    <input type="text" name="no" value="1"/> 
    <input type="text" name="nm" value="abcd"/> 
    <input type="submit"/> 
    </form>'''


class SimpleModel(BaseModel):
    no: int
    nm: str = ""

@app.post("/form", response_model=SimpleModel)
def form_post(form_data: SimpleModel = Form(...)):
    return form_data

但是，我收到HTTP错误：&Quot；422无法处理的实体&Quot；

{
    "detail": [
        {
            "loc": [
                "body",
                "form_data"
            ],
            "msg": "field required",
            "type": "value_error.missing"
        }
    ]
}

等效的cURL命令(由Firefox生成)为

curl 'http://localhost:8001/form' -H 'Content-Type: application/x-www-form-urlencoded' --data 'no=1&nm=abcd'

此处请求正文包含no=1&nm=abcd。

我做错了什么？

推荐答案

我找到了一个解决方案，可以帮助我们在FastAPI Forms中使用PYDANIC：)

我的代码：

class AnyForm(BaseModel):
    any_param: str
    any_other_param: int = 1

    @classmethod
    def as_form(
        cls,
        any_param: str = Form(...),
        any_other_param: int = Form(1)
    ) -> AnyForm:
        return cls(any_param=any_param, any_other_param=any_other_param)

@router.post('')
async def any_view(form_data: AnyForm = Depends(AnyForm.as_form)):
        ...

它在Swagger中显示为常用形式。

作为装饰者，它可以更通用：

import inspect
from typing import Type

from fastapi import Form
from pydantic import BaseModel
from pydantic.fields import ModelField

def as_form(cls: Type[BaseModel]):
    new_parameters = []

    for field_name, model_field in cls.__fields__.items():
        model_field: ModelField  # type: ignore

        new_parameters.append(
             inspect.Parameter(
                 model_field.alias,
                 inspect.Parameter.POSITIONAL_ONLY,
                 default=Form(...) if not model_field.required else Form(model_field.default),
                 annotation=model_field.outer_type_,
             )
         )

    async def as_form_func(**data):
        return cls(**data)

    sig = inspect.signature(as_form_func)
    sig = sig.replace(parameters=new_parameters)
    as_form_func.__signature__ = sig  # type: ignore
    setattr(cls, 'as_form', as_form_func)
    return cls

和用法如下

class Test1(BaseModel):
    a: str
    b: int


@as_form
class Test(BaseModel):
    param: str
    test: List[Test1]
    test1: Test1
    b: int = 1
    a: str = '2342'


@router.post('/me', response_model=Test)
async def me(request: Request, form: Test = Depends(Test.as_form)):
    return form

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