Angular2 get existing validators of a formcontrol

You can display error messages like this:

onValueChanged(data?: any) {
    if (!this.heroForm) { return; }
    const form = this.heroForm;
    for (const field in this.formErrors) {
            // clear previous error message (if any)
            this.formErrors[field] = '';
            const control = form.get(field);
            if (control && control.dirty && !control.valid) {
            const messages = this.validationMessages[field];
            for (const key in control.errors) {
                this.formErrors[field] += messages[key] + ' ';
            }
        }
    }
}
formErrors = {
    'name': '',
    'power': ''
};
validationMessages = {
    'name': {
        'required':      'Name is required.',
        'minlength':     'Name must be at least 4 characters long.',
        'maxlength':     'Name cannot be more than 24 characters long.',
        'forbiddenName': 'Someone named "Bob" cannot be a hero.'
    },
    'power': {
        'required': 'Power is required.'
    }
};

Refer: https://angular.io/docs/ts/latest/cookbook/form-validation.html#!#reactive-component-template

Reading validators from a control is currently not supported

See also https://github.com/angular/angular/issues/13461