plainToClass should always return a class-instance or throw

[tmtron]

I think plainToClass should always reutrn a class-instance or throw an exception.

Here's a simple example where this is not the case (using version 0.2.3):

class Test {
  @IsString()
  readonly table!: string;
}
// note, that we call it with a completely wrong type: string instead of JSON-object
const result = plainToClass(Test, 'not a class');

Then result is of type string (value = 'not a class').

I'd expect plainToClass to:

• return an instance of type Test where all properties remain undefined, or
• throw an exception

Not sure, if this is a bug or intended - maybe there's a good reason for the current behaviour that I am missing?

see also Stackoverflow Question

[NicoAiko]

I think so too. I have the problem as well that the object I try to transform might contain an unintended value of a type that it is not supposed to have.

Running that object through plainToClass kills the whole node process

[ViRuSTriNiTy]

Same here, I think it is one of the reasons one would use this lib. I thought this lib would save me some time as I don't need to manage all the nit bits when serializing / de-serializing data by myself. After reading this issue it's clear to me that this library doesn't do that.

[NoNameProvided]

I am sure there is an open issue for this somewhere. I agree, but it's a breaking change.

[MickL]

I also ran into this problem: I validated the response of an API which returned an error string instead of an json object. This was not catched by plainToClass() and class-validator validateSync() so my whole app ran into different errors.

[anuragphadnis]

Is this fixed yet or any recommended workaround?