issue: "Illegal constructor" error when using the classValidatorResolver with a file input

Version Number

7.15.4

Codesandbox/Expo snack

https://codesandbox.io/s/flamboyant-breeze-trm2p?file=/src/App.tsx

Steps to reproduce

1. Create a simple form with a file input e.g.

<input type="file" {...register('test')} />

1. Create a class for the validation schema e.g.

class ValidationSchema {
  test: any;
}

1. Give the validation class to the useForm hook e.g.

useForm< ValidationSchema >({ resolver: classValidatorResolver(ValidationSchema), });

1. Submit the form after selecting a .jpg file. You will see a “Illegal constructor” error

Expected behaviour

We shouldn’t get an error.

What browsers are you seeing the problem on?

Chrome, Safari

Relevant log output

Unhandled Runtime Error
TypeError: Illegal constructor

Code of Conduct

• I agree to follow this project’s Code of Conduct

[willdspd]

It works with the @williamdespard 's custom resolver because he is using Object.assign, we can’t use it in our case. It’s not compatible with nested data.

I’ve found a possible solution, I’m a beginner with class-validator, you may adapt the code below:

export class ValidationSchema {

  @Type(() => Object)

  @Transform(({ obj }: TransformFnParams) => {

    return obj.test;

  })

  test: File | null = null;

}

👉🏻 https://codesandbox.io/s/restless-wood-mw9mz

Thanks for this but it appears your solution doesn’t work in the sandbox provided. I get the error “Not enough arguments”

[jorisre]

It works with the @williamdespard 's custom resolver because he is using Object.assign, we can’t use it in our case. It’s not compatible with nested data.

I’ve found a possible solution, I’m a beginner with class-validator, you may adapt the code below:

export class ValidationSchema {
  @Type(() => Object)
  @Transform(({ obj }: TransformFnParams) => {
    return obj.test;
  })
  test: File | null = null;
}

👉🏻 https://codesandbox.io/s/restless-wood-mw9mz