Cannot assign only the "dataChange" property of a read only object # # ValidationComponent>

I am trying to use two-way binding in Angular 4. Here is my component code:

@Component({
    selector: 'form-validation',
    templateUrl: './form.validation.template.html',
    encapsulation: ViewEncapsulation.None
})

export class ValidationComponent {

    @Input() data;

    @Output dataChange = new EventEmitter();

    //...

}

      

        
        
        
      

    

But when I try to use it on something like this:

<form-validation [(data)]="data"></form-validation>

      

        
        
        
      

    

I am getting this error on Chrome console:

Cannot assign to read only property 'dataChange' of object '#<ValidationComponent>'

      

        
        
        
      

    

A property data

is an array of a specific type, but even if I report that type or initialize the property, an error occurs.