disable-control.directive.ts

import {Directive, Input} from '@angular/core';
import {NgControl} from '@angular/forms';

@Directive({
  selector: '[smartDisableControl]'
})
export class DisableControlDirective {

    @Input() set disableControl( condition : boolean ) {
        const action = condition ? 'disable' : 'enable';
        this.ngControl.control[action]();
    }

    constructor( private ngControl : NgControl ) {
    }

}