Typescript Class-Validator Contains multiple strings (IsEmail)

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I have been using the class-validator decorator library to validate dto objects and would like to create a domain whitelist for the @IsEmail decorator. The library includes a @Contains decorator, which can be used for a single string (seed), but I would like to input an array of valid strings instead. Is this possible?

current

  @Contains('@mydomain.com')
  @IsEmail()
  public email: string;

desired

  @Contains(['@mydomain, @yourdomain, @wealldomain, @fordomain'])
  @IsEmail()
  public email: string;

If this is not possible, I would appreciate any direction on how to implement a custom decorator which serves this purpose.

Thanks.

1 Answers

Consider this example:

const Contains = <Domain extends `@${string}`, Domains extends Domain[]>(domains: [...Domains]) =>
    (target: Object, propertyKey: string) => {
        let value: string;
        const getter = () => value
        const setter = function (newVal: Domain) {
            if (domains.includes(newVal)) {
                value = newVal;
            }
            else {
                throw Error(`Domain should be one of ${domains.join()}`)
            }
        };
        Object.defineProperty(target, propertyKey, {
            get: getter,
            set: setter
        });
    }

class Greeter {
    @Contains(['@mydomain', '@wealldomain'])
    greeting: string;
    constructor(message: string) {
        this.greeting = message;
    }

}

const ok = new Greeter('@mydomain'); // ok
const error = new Greeter('234'); // runtime error

Playground

If you provide invalid email domain it will trigger runtime error. It is up to you how you want to implement validation logic. It might be not necessary a runtime error

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