Custom Validator on reactive form for password and

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="[e-mail]">
            <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">Contraseña:</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 contraseña</p>
          </div>
          <div class="form-group">
            <label for="confirmedPassword" class="control-label">Confirmar Contraseña:</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 contraseña no puede estar vacía</p>
            <p class="help-block" *ngIf="signUpForm.get('confirmedPassword').hasError('passwordMismatch') && signUpForm.get('confirmedPassword').touched">Las contraseñas 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;
        }
    }
      }


    }

Answer 1

The issue is that you are mixing the reactive forms module with the input approach. This is causing you to get undefined when passing the values to the validator.

You don't need to bind to the ng-model when using the reactive forms. Instead, you should access the value of the fields from the Instance of FormGroup.

I do something like this in an app to validate the passwords match.

public Credentials: FormGroup;

ngOnInit() {
    this.Credentials = new FormGroup({});
    this.Credentials.addControl('Password', new FormControl('', [Validators.required]));
    this.Credentials.addControl('Confirmation', new FormControl(
        '', [Validators.compose(
            [Validators.required, this.validateAreEqual.bind(this)]
        )]
    ));
}

private validateAreEqual(fieldControl: FormControl) {
    return fieldControl.value === this.Credentials.get("Password").value ? null : {
        NotEqual: true
    };
}

Note that the validator expects a FormControl field as a parameter and it compares the value of the field to that of the value of the Password field of the Credentials FormGroup.

In the HTML make sure to remove the ng-model.

<input type="password" class="form-control" formControlName="confirmedPassword"  title="Please re-enter your password" >
<!-- AND -->
<input type="password" class="form-control" formControlName="password" title="Please enter your password">

Hope this helps!

Answer 2

Please update FormGroup code like below in Angular5

 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])
    }, this.pwdMatchValidator);

Add pwdMatchValidator function in your component

pwdMatchValidator(frm: FormGroup) {
    return frm.get('password').value === frm.get('confirmedPassword').value
       ? null : {'mismatch': true};
 }

Add validation message in your template

<span *ngIf="confirmedPassword.errors || signUpForm .errors?.mismatch">
              Password doesn't match
            </span>

Please find the below angular material working component.

Component Templete Code password.component.html

 <form class="cahnge-pwd-form" (ngSubmit)="onSubmit()" name="passwordForm" [formGroup]="passwordForm" #formDir="ngForm">
      <div fxLayout='column'>
    <mat-form-field>
      <input matInput name="password" placeholder="Password" [type]="hide ? 'text' : 'password'" formControlName="password" required>
      <mat-icon matSuffix (click)="hide = !hide">{{hide ? 'visibility_off' : 'visibility'}}</mat-icon>
      <mat-error *ngIf="password.invalid && (password.dirty || password.touched || isSubmit)">
        <span *ngIf="password.errors.required">
          Please enter a Password.
        </span>
        <span *ngIf="password.errors.maxlength">
          Please enter a Email no more than 16 characters.
        </span>
        <span *ngIf="password.errors.minlength">
          Please enter a password at least 6 characters.
        </span>
      </mat-error>
    </mat-form-field>
    <mat-form-field>
      <input matInput name="password" placeholder="Confirm Password" [type]="confirm_hide ? 'text' : 'password'" formControlName="confirm_password"
        required>
      <mat-icon matSuffix (click)="confirm_hide = !confirm_hide">{{confirm_hide ? 'visibility_off' : 'visibility'}}</mat-icon>
      <mat-error *ngIf="(confirm_password.invalid && (confirm_password.dirty || confirm_password.touched || isSubmit) || passwordForm.errors?.mismatch)">
        <span *ngIf="confirm_password.errors || passwordForm.errors?.mismatch">
          Password doesn't match
        </span>
      </mat-error>
    </mat-form-field>
    <div fxLayout='row' fxLayoutGap="10px">
      <button type="submit" mat-raised-button color="primary">Submit</button>
      <button type="button" (click)="formDir.resetForm(passwordForm)" mat-raised-button color="warn">Cancel</button>
    </div>
  </div>
</form>

Component Code : password.component.ts

import { Component, OnInit, AfterViewInit } from '@angular/core';
import { FormControl, FormGroup, Validators, FormBuilder } from '@angular/forms';
import { ToastrService } from 'ngx-toastr';
import { Router, ActivatedRoute, ParamMap } from '@angular/router';
import { PasswordService } from './password.service';
import { PasswordValidation  } from './confirm';

@Component({
  selector: 'app-password',
  templateUrl: './password.component.html',
  styleUrls: ['./password.component.css']
})
export class PasswordComponent implements OnInit {
  passwordForm: FormGroup;
  isSubmit: boolean;
  constructor(private router: Router, private passwordService: PasswordService, private toastrService: ToastrService, private route: ActivatedRoute) { }
  ngOnInit() {
    this.passwordForm = new FormGroup({
      'password': new FormControl('', [
        Validators.required,
        Validators.minLength(6),
        Validators.maxLength(16),
      ]),
      'confirm_password': new FormControl('', [
         Validators.required,
        Validators.minLength(6),
        Validators.maxLength(16),
      ]),
    }, this.pwdMatchValidator);

  }
 pwdMatchValidator(frm: FormGroup) {
    return frm.get('password').value === frm.get('confirm_password').value
       ? null : {'mismatch': true};
 }

  get password() { return this.passwordForm.get('password'); }
  get confirm_password() { return this.passwordForm.get('confirm_password'); }

  onSubmit(formvalue):boolean {
    this.isSubmit = true;
    if (this.passwordForm.invalid) {
      return false;
    } else {
      this.passwordService.updatePassword(this.passwordForm.value)
      .subscribe((res) => {
        if (res.status == 'success') {
          this.toastrService.success(res.msg);
          this.router.navigate(['/change-password']);
        }
      })
      return true;
    }

  }

}

Answer 3

There are two types of validators: FormGroup validator and FormControl validator. To verify two passwords match, you have to add a FormGroup validator. Below is my example:

Note: this.fb is the injected FormBuilder

this.newAccountForm = this.fb.group(
  {
    newPassword: ['', [Validators.required, Validators.minLength(6)]],
    repeatNewPassword: ['', [Validators.required, Validators.minLength(6)]],
  }, 
  {validator: this.passwordMatchValidator}
);

passwordMatchValidator(frm: FormGroup) {
  return frm.controls['newPassword'].value === frm.controls['repeatNewPassword'].value ? null : {'mismatch': true};
}

and in the templeate:

<div class="invalid-feedback" *ngIf="newAccountForm.errors?.mismatch && (newAccountForm.controls['repeatNewPassword'].dirty || newAccountForm.controls['repeatNewPassword'].touched)">
  Passwords don't match.
</div>

The key point here is to add the FormGroup validator as the second parameter to the group method.

Answer 4

const form = new FormGroup({
  password: new FormControl('', Validators.minLength(2)),
  passwordConfirm: new FormControl('', Validators.minLength(2)),
}, passwordMatchValidator);

function passwordMatchValidator(g: FormGroup) {
   return g.get('password').value === g.get('passwordCenter code hereonfirm').value
      ? null : {'mismatch': true};
}

Have to create a new service and you can call the created service while you want to validate the password and confirmation fields.

Answer 5

import {AbstractControl, FormBuilder, FormGroup, Validators} from

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

<div class="form-group row" formGroupName="passwords">
 <div class="form-group">
     <label for="password" class="control-label">Contraseña:</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 contraseña</p>
           </div>
          <div class="form-group">
            <label for="confirmedPassword" class="control-label">Confirmar Contraseña:</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">La confirmación de contraseña no puede estar vacía</p>
            <p class="help-block" *ngIf="signUpForm.get('confirmedPassword').hasError('passwordMismatch') && signUpForm.get('confirmedPassword').touched">Las contraseñas no coinciden</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>

Answer 6

When you're creating the validator, you're passing in the values of password and confirmedPassword, but changes in those values will not be reflected in the validator.

The two options I see are:

1. define your validator on the FormGroup, and look up the values from the two controls you want to compare; or
2. since you're binding to this already, use this.password and this.confirmedPassword in your validator.