Bug Report

Describe the bug

When using the CldUploadWidget widget to sign the URL, it seems that the request it sents is not application/json. Is it possible to change this behavior?

FastAPI backend is returning a 422 response in the case it's a text/plain;charset=UTF-8 and ideally would be nice to use json

Of course, with a nodejs server; it doesn't really care about the type and transform the data into an object, but with python and Fastapi server, it's slightly different.

Is this a regression?

Nop

Steps To Reproduce the error

Create a fast API backend server with a route that takes a BaseModel to transform the payload into an object and request the route

Expected behaviour

I expect the request being a content-type application/json, here is the 422 response

{
    "detail": [
        {
            "type": "missing",
            "loc": [
                "body"
            ],
            "msg": "Field required",
            "input": null,
            "url": "https://errors.pydantic.dev/2.4/v/missing"
        }
    ]
}

Your environment

• OS: Mac
• Node version: 21.1
• Npm version: 10.2.0
• Browser name and version: Chrome and Postman