Considere el ejemplo proporcionado en la sección Decoradores de validación personalizados :

 // Decorator definition import { registerDecorator, ValidationOptions, ValidationArguments } from 'class-validator'; export function IsLongerThan(property: string, validationOptions?: ValidationOptions) { return function (object: Object, propertyName: string) { registerDecorator({ name: 'isLongerThan', target: object.constructor, propertyName: propertyName, constraints: [property], options: validationOptions, validator: { validate(value: any, args: ValidationArguments) { const [relatedPropertyName] = args.constraints; const relatedValue = (args.object as any)[relatedPropertyName]; return typeof value === 'string' && typeof relatedValue === 'string' && value.length > relatedValue.length; // you can return a Promise<boolean> here as well, if you want to make async validation }, }, }); }; }

 // Decorator usage import { IsLongerThan } from './IsLongerThan'; export class Post { title: string; @IsLongerThan('title', { /* you can also use additional validation options, like "groups" in your custom validation decorators. "each" is not supported */ message: 'Text must be longer than the title', }) text: string; }

¿Cómo puedo establecer/anular la cadena de message de forma condicional, dentro del método de validator ? es posible?