Validation messages directive

control-messages.ts

import {Component, Host} from 'angular2/core';
import {NgFormModel} from 'angular2/common';
import {ValidationService} from './validation.service';

@Component({
  selector: 'control-messages',
  inputs: ['controlName: control'],
  template: `<p *ngIf="errorMessage !== null">{{errorMessage}}</p>`
})
export class ControlMessages {
  controlName: string;
  constructor(@Host() private _formDir: NgFormModel) { }

  get errorMessage():string {
    // Acha o controle no component pai (Host/Parent)
    let c = this._formDir.form.find(this.controlName);

    // Para cada attr no objeto errors
    for (let propertyName in c.errors) {
      
      // Confirma que existe um erro e que o componente foi "tocado"
      if (c.errors.hasOwnProperty(propertyName) && c.touched) {
        return ValidationService.getValidatorErrorMessage(propertyName);
      }
      
    }

    return null;
  }
}