How to reset form validation on submission of the form in ANGULAR 2

app.component.html

The #formDirective="ngForm" and passing the formDirective to the onSubmit method is crucial for resetting error styles such as mat-error. Check #4190 to follow this bug and in-depth explanation why it's needed and how it works under the hood.

<form [formGroup]="contactForm" (ngSubmit)="onSubmit(contactForm.value, formDirective)" #formDirective="ngForm"> 
  <!-- Your input elements... -->
  <button [disabled]="!contactForm.valid">Submit</button>
</form>

app.component.ts

Remember about the FormGroupDirective which you need to import from @angular/forms (Angular/Material 9). To make the form empty call this.contactForm.reset(); and the form will be invalid, it's fine. However, you also need to reset the undesired validators styles, and this is a different method, i.e. formDirective.resetForm();.

Notice difference between formDirective and formData with its different built-in methods.

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

public contactForm: FormGroup = this.formBuilder.group({
  // Your input elements...
});

public onSubmit(
  formData: FormGroup,
  formDirective: FormGroupDirective
): void {
  this.contactForm.reset(); // Reset form data
  formDirective.resetForm(); // Reset the ugly validators
}

from.resetForm()

I've tried pretty much everything, and the only thing I found that actually resets form.submitted to false is the following:

In your template, send your form into the submit function:

<form name="form" class="form-horizontal" (ngSubmit)="f.form.valid && submit(f)" #f="ngForm" novalidate>

In your component.ts file, have the following:

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

// get the passed in variable from the html file
submit(myForm: NgForm): void {

    console.log(myForm.form.status, myForm.form.dirty, myForm.form.pristine, myForm.form.untouched, myForm.submitted, myForm.dirty, myForm.pristine, myForm.untouched);

    // This is the key!
    myForm.resetForm();

    console.log(myForm.form.status, myForm.form.dirty, myForm.form.pristine, myForm.form.untouched, myForm.submitted, myForm.dirty, myForm.pristine, myForm.untouched);


}

The console.log values output the following - notice it resets all values.

VALID true false false true true false false

INVALID false true true false false true true

Here's how it currently works with Angular 4.1.0 - 5.1.3:

class YourComponent {
    @ViewChild("yourForm")
    yourForm: NgForm;


    onSubmit(): void {
        doYourThing();

        // yourForm.reset(), yourForm.resetForm() don't work, but this does:
        this.yourForm.form.markAsPristine();
        this.yourForm.form.markAsUntouched();
        this.yourForm.form.updateValueAndValidity();
    }
}