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How can I manually set an Angular form field as invalid?

I am working on a login form and if the user enters invalid credentials we want to mark both the email and password fields as invalid and display a message that says the login failed. How do I go about setting these fields to be invalid from an observable callback?

Template:

<form #loginForm="ngForm" (ngSubmit)="login(loginForm)" id="loginForm">
  <div class="login-content" fxLayout="column" fxLayoutAlign="start stretch">
    <md-input-container>
      <input mdInput placeholder="Email" type="email" name="email" required [(ngModel)]="email">
    </md-input-container>
    <md-input-container>
      <input mdInput placeholder="Password" type="password" name="password" required [(ngModel)]="password">
    </md-input-container>
    <p class='error' *ngIf='loginFailed'>The email address or password is invalid.</p>
    <div class="extra-options" fxLayout="row" fxLayoutAlign="space-between center">
     <md-checkbox class="remember-me">Remember Me</md-checkbox>
      <a class="forgot-password" routerLink='/forgot-password'>Forgot Password?</a>
    </div>
    <button class="login-button" md-raised-button [disabled]="!loginForm.valid">SIGN IN</button>
     <p class="note">Don't have an account?<br/> <a [routerLink]="['/register']">Click here to create one</a></p>
   </div>
 </form>

Login method:

 @ViewChild('loginForm') loginForm: HTMLFormElement;

 private login(formData: any): void {
    this.authService.login(formData).subscribe(res => {
      alert(`Congrats, you have logged in. We don't have anywhere to send you right now though, but congrats regardless!`);
    }, error => {
      this.loginFailed = true; // This displays the error message, I don't really like this, but that's another issue.
      this.loginForm.controls.email.invalid = true;
      this.loginForm.controls.password.invalid = true; 
    });
  }

In addition to setting the inputs invalid flag to true I've tried setting the email.valid flag to false, and setting the loginForm.invalid to true as well. None of these cause the inputs to display their invalid state.

over 4 years ago · Santiago Trujillo
3 answers
Answer question

0

in component:

formData.form.controls['email'].setErrors({'incorrect': true});

and in HTML:

<input mdInput placeholder="Email" type="email" name="email" required [(ngModel)]="email"  #email="ngModel">
<div *ngIf="!email.valid">{{email.errors| json}}</div>
over 4 years ago · Santiago Trujillo Report

0

Adding to Julia Passynkova's answer

To set validation error in component:

formData.form.controls['email'].setErrors({'incorrect': true});

To unset validation error in component:

formData.form.controls['email'].setErrors(null);

Be careful with unsetting the errors using null as this will overwrite all errors. If you want to keep some around you may have to check for the existence of other errors first:

if (isIncorrectOnlyError){
   formData.form.controls['email'].setErrors(null);
}
over 4 years ago · Santiago Trujillo Report

0

In new version of material 2 which its control name starts with mat prefix setErrors() doesn't work, instead Juila's answer can be changed to:

formData.form.controls['email'].markAsTouched();
over 4 years ago · Santiago Trujillo Report
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