TYPESCRIPT

Custom validation for phone-number using class-validator package

import { ClassConstructor } from 'class-transformer';
import {
    ValidationOptions,
    registerDecorator,
    ValidationArguments,
    ValidatorConstraintInterface,
    ValidatorConstraint,
} from 'class-validator';
import { PhoneNumberUtil } from 'google-libphonenumber';
import * as iso from 'i18n-iso-countries';

// phone-number validator
export const IsValidNumberOf = <T>(
    type: ClassConstructor<T>,
    property: (o: T) => any,
    validationOptions?: ValidationOptions,
) => {
    return (object: any, propertyName: string) => {
        registerDecorator({
            target: object.constructor,
            propertyName,
            options: validationOptions,
            constraints: [property],
            validator: IsValidNumberOfConstraint,
        });
    };
};

@ValidatorConstraint({ name: 'IsValidNumberOf', async: true })
export class IsValidNumberOfConstraint implements ValidatorConstraintInterface {
    validate(value: any, args: ValidationArguments) {
        const util = PhoneNumberUtil.getInstance();

        const [fn] = args.constraints;
        // get the value of the country Field
        const countryCode = fn(args.object);
        // check if the country is valid even though it is checked at class level 
        const isValidISOCode = iso.isValid(countryCode);
        if (!isValidISOCode) {
            return false;
        }

        // Checks if the value (number) belongs in the extracted countryCode 
        const formattedPhoneNumber = util.parse(value, countryCode);
        const isValidPhoneNumber = util.isValidNumberForRegion(formattedPhoneNumber, countryCode);
        if (!isValidPhoneNumber) {
            return false;
        }

        return true;
    }

    defaultMessage(args: ValidationArguments) {
        // const [constraintProperty]: (() => any)[] = args.constraints;
        return `${args.property} must be a valid phone-number in the specified country`;
    }
}

// user
import { IsISO31661Alpha2, IsNotEmpty } from 'class-validator';
import { IsValidNumberOf } from '../../validators/is-valid-number-of.validator';
import { IPhoneNumber } from '../../interfaces/shared/phone-number.interface';

export class PhoneNumberDTO implements IPhoneNumber {
    @IsValidNumberOf(PhoneNumberDTO, (o: { country: any; }) => o.country)
    number: string;

    @IsNotEmpty()
    @IsISO31661Alpha2()
    country: string;
}