How to validate form element without using reactive forms?

Question

I want to validate an element without using Reactive Forms, I am using two way binding like below:

 <input
                    type="text"
                    class="form-control"
                    autocomplete="off"
                    [required]="fieldDefinition.required"
                    [disabled]="fieldDefinition.disabled"
                    [(ngModel)]="fieldDefinition.fieldvalue"
                />

How to highlight elements by red color after clicking on a button if they are required? So, I need to validate all fields after button click.

Answer 1

Angular add the class ng-invalid ng-touched to the inputs with [(ngModel)] -also if you use ReactiveForms

so, you can declare a variable

submitted=false;

And in button

<button (click)="submitted=true">submit</button>

Your inputs add the class submitted when the variable becomes true

<input [class.submitted]="submitted" ....>

And you can define a .css like

.submitted.ng-invalid
{
  border-color:red
}

You can see a simple example in this stackblitz