disable-form-group.directive.ts

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

@Directive({
    selector: '[disableFormGroup]',
})
export class DisableFormGroupDirective {
    @Input() form: any;
    @Input() formGroupName: string;
    @Input()
    set disableFormGroup(disabled: boolean) {
        const method = disabled ? 'disable' : 'enable';
        this.form.get(this.formGroupName)[method]();
    }
}