python - 使用 JSON 数据上传文件时 FastAPI 多部分/表单数据错误

Question

我的 Pydantic 模型看起来像这样:

class Banner:
    title: str
    text: str

我的路线是这样的:

@router.post('', status_code=201)
async def create_banner(
    banner: Banner,
    photo: UploadFile = File(...)  # multipart/form-data

):
    return await Banners.create(banner.dict())

但是 FastAPI 返回以下错误:

Answer 1

根据FastAPI docs :

You can declare multiple File and Form parameters in a path operation,but you can't also declare Body fields that you expect to receive asJSON, as the request will have the body encoded usingmultipart/form-data instead of application/json.

This is not a limitation of FastAPI, it's part of the HTTP protocol.

并且在传递对象时，FastAPI 会尝试将其视为正文规范，而不是表单字段。这意味着，您必须将 banner 参数显式定义为表单字段:

@router.post('', status_code=201)
async def create_banner(
    banner: Banner = Form(...),
    photo: UploadFile = File(...)  # multipart/form-data

):
    return await Banners.create(banner.dict())

还要确保您的 Banner 对象是有效的 pydantic 模型，因为 FastAPI 无法在此上下文中正确识别裸对象。