How can my class-validator validate union string | number?

Question

I have an simple DTO class for validation

class SearchIssuerDto {
    search: string | number;
}

What is the correct way to validate the search param that it can accept an string or a number ?

Answer 1

You can create a custom validator for that:

@ValidatorConstraint({ name: 'string-or-number', async: false })
export class IsNumberOrString implements ValidatorConstraintInterface {
  validate(text: any, args: ValidationArguments) {
    return typeof text === 'number' || typeof text === 'string';
  }

  defaultMessage(args: ValidationArguments) {
    return '($value) must be number or string';
  }
}

Usage:

class SearchIssuerDto {
  @IsDefined()
  @Validate(IsNumberOrString)
  search: number | string;
}