How to validate optional field in angular 2?

Question

i have an email field which is optional but if has value should match the email pattern ?

what about if the form has many optional fields ,like website ,phone ,etc ?

by the way am using FormBuilder, FormGroup, Validators form @angular/forms

Answer 1

Solved this by creating an optionalValidator:

import { ValidatorFn, AbstractControl, Validators } from '@angular/forms';

export function optionalValidator(validators?: (ValidatorFn | null | undefined)[]): ValidatorFn {
    return (control: AbstractControl): { [key: string]: any } => {

        return control.value ? Validators.compose(validators)(control) : null;
    };
}

In my reactive form:

this.form = this._fb.group({
      email: [this.contact.email, [optionalValidator([Validators.maxLength(255), Validators.email])]]
    });