Angular 2 validator not working as expected

Question

I got this validator:

export const PasswordsEqualValidator = (): ValidatorFn => {

  return (group: FormGroup): Observable<{[key: string]: boolean}> => {

    const passwordCtrl: FormControl = <FormControl>group.controls.password;
    const passwordAgainCtrl: FormControl = <FormControl>group.controls.passwordAgain;

    const valid = passwordCtrl.value.password === passwordAgainCtrl.value.passwordAgain;

    return Observable.of(valid ? null : {
      passwordsEqual: true
    });
  };
};

Which is used in this form:

  public signupForm: FormGroup = this.fb.group({
    email: ['', Validators.required],
    passwords: this.fb.group({
      password: ['', Validators.required],
      passwordAgain: ['', Validators.required]
    }, {validator: CustomValidators.passwordsEqual()})
  });

Part of the template which uses it:

<div formGroupName="passwords">
  <div class="form-control" [ngClass]="{error: !signupForm.get('passwords').valid}">
    <label class="label" for="password">Password</label>
    <input class="input" id="password" formControlName="password" type="password">
  </div>
  <div class="form-control" [ngClass]="{error: !signupForm.get('passwords').valid}">
    <label class="label" for="password-again">Password again</label>
    <input class="input" id="password-again" formControlName="passwordAgain" type="password">
  </div>
</div>

The problem is that even when the passwords match, it still shows the error. I've looked at a number of different similar questions but most of em are a bit cluttered and outdated so I wanted to write a cleaner solution.

I'm guessing there's just a small adjustment needed but I just can't seem to figure it out.

Answer 1

try this, because you need compare 2 value and the validator is not async validator, you could return only boolean instead of Observable

export const PasswordsEqualValidator = (): ValidatorFn => {

  return (group: FormGroup): boolean => {

    const passwordCtrl: FormControl = <FormControl>group.controls.password;
    const passwordAgainCtrl: FormControl = <FormControl>group.controls.passwordAgain;

    const valid = passwordCtrl.value === passwordAgainCtrl.value;

    return valid ? null : {
      passwordsEqual: true
    };
  };
};

btw, using this method for best practice:

export const PasswordsEqualValidator = (): ValidatorFn => {

  return (group: FormGroup): boolean => {

    const passwordCtrl: FormControl = group.get('password');
    const passwordAgainCtrl: FormControl = group.get('passwordAgain');

    const valid = passwordCtrl.value === passwordAgainCtrl.value;

    return valid ? null : {
      passwordsEqual: true
    };
  };
};

demo here: http://plnkr.co/edit/9PzGSIuBhvNz0fpJxTlS?p=preview