javascript - Custom Validator on reactive form for password and confirm password matching getting undefined parameters into Angular 4

Question

I'm trying to implement a custom validator to check if the password and password confirm are equal. The problem is that the validator is getting undefined password and confirmedPassword parameters. How do I make this work. The function works cause if I change the condition to === instead of !== it throws the error correctly when the fields are the same. Does anyone know which is the error here?

signup.component.html

<div class="col-md-7 col-md-offset-1 col-sm-7">
  <div class="block">
    <div class="well">
        <form (onSubmit)="onSubmit()" [formGroup]="signUpForm">
          <div class="form-group">
            <label for="username" class="control-label">Nombre de usuario:</label>
            <input type="text" class="form-control" formControlName="username"  title="Please enter your username" placeholder="username">
            <p class="help-block" *ngIf="signUpForm.get('username').hasError('required') && signUpForm.get('username').touched">El nombre de usuario es obligatorio</p>
            <p class="help-block" *ngIf="signUpForm.get('username').hasError('minlength') && signUpForm.get('username').touched">El nombre de usuario debe tener al menos 6 caracteres</p>
            <p class="help-block" *ngIf="signUpForm.get('username').hasError('maxlength') && signUpForm.get('username').touched">El nombre de usuario debe tener menos de 15 caracteres</p>
          </div>
          <div class="form-group">
            <label for="email" class="control-label">E-mail:</label>
            <input class="form-control" formControlName="email" title="Please enter your email" placeholder="[email protected]">
            <p class="help-block" *ngIf="signUpForm.get('email').hasError('required') && signUpForm.get('email').touched">La dirección de email es obligatoria</p>
            <p class="help-block" *ngIf="signUpForm.get('email').hasError('email') && signUpForm.get('email').touched">Debe ingresar una dirección de correo válida</p>
          </div>
          <div class="form-group">
            <label for="password" class="control-label">Contrase?a:</label>
            <input type="password" class="form-control" formControlName="password" title="Please enter your password" [(ngModel)]="password">
            <p class="help-block" *ngIf="signUpForm.get('password').hasError('required') && signUpForm.get('password').touched">Debe ingresar una contrase?a</p>
          </div>
          <div class="form-group">
            <label for="confirmedPassword" class="control-label">Confirmar Contrase?a:</label>
            <input type="password" class="form-control" formControlName="confirmedPassword"  title="Please re-enter your password" [(ngModel)]="confirmedPassword">
            <p class="help-block" *ngIf="signUpForm.get('confirmedPassword').hasError('required') && signUpForm.get('confirmedPassword').touched">La confirmación de contrase?a no puede estar vacía</p>
            <p class="help-block" *ngIf="signUpForm.get('confirmedPassword').hasError('passwordMismatch') && signUpForm.get('confirmedPassword').touched">Las contrase?as no coinciden</p>
          </div>
          <button type="submit" class="btn btn-success" [disabled]="!signUpForm.valid">Registrarse</button>
          <a routerLink="/signin" class="btn btn-default" style="">Ya tenes usuario? Logueate</a> {{ creationMessage }}
        </form>

      </div>

  </div>
</div>

signup.component.ts

import { Component, OnInit, ViewChild, Input } from '@angular/core';
import { FormControl, FormGroup, Validators } from '@angular/forms';
import { CustomValidators } from '../../shared/custom-validators';
import { Observable } from 'rxjs/Observable';

@Component({
  selector: 'app-signup',
  templateUrl: './signup.component.html',
  styleUrls: ['./signup.component.sass']
})
export class SignupComponent implements OnInit {

  signUpForm: FormGroup;
  user = {
    username: '',
    email: '',
    password: ''
  };
  submitted = false;
  @Input() password='';
  @Input() confirmedPassword='';

  constructor() { }

  ngOnInit() {

    this.signUpForm = new FormGroup({
      'username': new FormControl(null, [Validators.required, Validators.minLength(6), Validators.maxLength(15)]),
      'email': new FormControl(null, [Validators.required, Validators.email, Validators.minLength(5)]),
      'password': new FormControl(null, [Validators.required]),
      'confirmedPassword': new FormControl(null, [Validators.required, CustomValidators.passwordsMatch(this.password,this.confirmedPassword).bind(this)])
    });
  }

  onSubmit() {
    if (this.signUpForm.valid) {
      console.log(this.signUpForm.value);
    }
  }

}

custom-validators.ts

    import { FormControl } from '@angular/forms';

    export class CustomValidators{

    public static passwordsMatch(password: string, confirmedPassword: string) {

     return (control: FormControl) : { [s: string]: boolean } =>{
       //getting undefined values for both variables
       console.log(password,confirmedPassword);
        //if I change this condition to === it throws the error if the 
//  two fields are the same, so this part works
        if (password !== confirmedPassword) {
          return { 'passwordMismatch': true }
        } else {
          //it always gets here no matter what
          return null;
        }
    }
      }


    }

question from:https://stackoverflow.com/questions/44449673/custom-validator-on-reactive-form-for-password-and-confirm-password-matching-get

Answer 1

import {AbstractControl, FormBuilder, FormGroup, Validators} from

set your password input into the group and no need to use "ngModel".

<div class="form-group row" formGroupName="passwords">
  <div class="form-group">
     <label for="password" class="control-label">Contrase?a:</label>
     <input type="password" class="form-control" formControlName="password" title="Please enter your password">
     <p class="help-block" *ngIf="signUpForm.get('password').hasError('required') && signUpForm.get('password').touched">Debe ingresar una contrase?a</p>
  </div>
  <div class="form-group">
     <label for="confirmedPassword" class="control-label">Confirmar Contrase?a:</label>
     <input type="password" class="form-control" formControlName="confirmedPassword"  title="Please re-enter your password">
     <p class="help-block" *ngIf="signUpForm.get('confirmedPassword').hasError('required') && signUpForm.get('confirmedPassword').touched">Password must be required</p>
     <p class="help-block" *ngIf="signUpForm.get('confirmedPassword').hasError('passwordMismatch') && signUpForm.get('confirmedPassword').touched">password does not match</p>
  </div>

     buildForm(): void {
            this.userForm = this.formBuilder.group({
                passwords: this.formBuilder.group({
                    password: ['', [Validators.required]],
                    confirm_password: ['', [Validators.required]],
                }, {validator: this.passwordConfirming}),

            });
        }

add this custom function for validate password and confirm password

  passwordConfirming(c: AbstractControl): { invalid: boolean } {
    if (c.get('password').value !== c.get('confirm_password').value) {
        return {invalid: true};
    }
}

Display error when password does not match

<div style='color:#ff7355' *ngIf="userForm.get(['passwords','password']).value != userForm.get(['passwords','confirm_password']).value && userForm.get(['passwords','confirm_password']).value != null">
  Password does not match</div>