I am trying to create a DTO class. But I am having issues finding a proper way to exclude undeclared properties. So if some one tries to create a DTO class and adds extra properties that are not declared inside the class then those properties should be ignored and not be added.
import { IsString, MinLength } from 'class-validator'
export class CreateUserDto {
@IsString()
email: string
@IsString()
@MinLength(6)
password: string
@IsString()
firstname: string
@IsString()
lastname: string
constructor (payload: any) {
const dto = Object.assign(this, payload)
console.log(dto)
}
}
For only 4 fields, I'd rather manually type out 4 lines to assign them each, but I guess if you have more DTO's with a lot more fields it could help with a more versatile method.
Here I've used Object.entries and Object.fromEntries along with a filter to exclude properties we don't need:
const dto = Object.assign(this, Object.fromEntries(Object.entries(payload).filter(([k]) => keys.includes(k))))
And keys would be something like:
["email", ...]
You can also make this a function for reusability or even a decorator too.