title: Angular 2 form validation, minLength validator is not working
body: <p>I have following Angular 2 form:</p>
  
  <pre><code>&lt;register&gt;
      &lt;form [ngFormModel] = "registrationForm"&gt;
          &lt;div class = "form-group"&gt;
              &lt;label class = "control-label" for="email"&gt;Email&lt;/label&gt;
              &lt;input class = "form-control" type="email" id="email" ngControl="email" #email="ngForm"&gt;
          &lt;/div&gt;
          &lt;div *ngIf = "email.touched &amp;&amp; email.errors"&gt;
              &lt;div *ngIf = "!email.errors.required &amp;&amp; email.errors.underscoreNotFound" class = "alert alert-danger"&gt;
                  &lt;span&gt;Underscore is required&lt;/span&gt; 
              &lt;/div&gt;
              &lt;div *ngIf = "email.errors.required" class = "alert alert-danger"&gt;
                  &lt;span&gt;Email is required&lt;/span&gt;
              &lt;/div&gt;
          &lt;/div&gt;
          &lt;div class = "form-group"&gt;
              &lt;label class = "control-label" for="password"&gt;Password&lt;/label&gt;
              &lt;input class = "form-control" type="password" id="password" ngControl="password" #password="ngForm"&gt;
          &lt;/div&gt;
          &lt;div *ngIf = "password.touched &amp;&amp; password.errors"&gt;
              &lt;div *ngIf = "password.errors.minLength &amp;&amp; !password.errors.required" class = "alert alert-danger"&gt;
                  &lt;span&gt;Password should contain 6 characters&lt;/span&gt;
              &lt;/div&gt;  
              &lt;div *ngIf = "password.errors.required" class = "alert alert-danger"&gt;
                  &lt;span&gt;Password is required&lt;/span&gt;
              &lt;/div&gt;          
          &lt;/div&gt;
      &lt;/form&gt;
  &lt;/register&gt;
  </code></pre>
  
  <p>This is my Component where I have implemented validators:</p>
  
  <pre><code>import {Component} from '@angular/core';
  import {Control, ControlGroup, FormBuilder, Validators} from '@angular/common';
  import {CustomValidator} from './CustomValidator';
  
  @Component({
      selector: 'register',
      templateUrl: './app/authentication/register_validation/register.html',
  })
  
  export class RegisterComponent{
      registrationForm: ControlGroup;
  
      constructor(formBuilder:FormBuilder)
      {
          this.registrationForm = formBuilder.group({
              email: ['',Validators.compose([Validators.required, CustomValidator.underscore])], 
              password: ['',Validators.compose([Validators.required,Validators.minLength(6)])]
          });
      }
  
  }
  </code></pre>
  
  <p>In this form, <code>email</code> field is working fine for both validators i.e. when I do not type anything , it gives <code>"Email is required"</code> message, when I start typing something, it gives <code>"Underscore is required"</code> message and when I type <code>"_"</code> all error messages disappears. However, when I try to apply such 2 validators on <code>password</code> field, it's not working. When I do not type password it gives message as <code>"Password is required"</code>. But when I type something less than 6 characters, <code>minLength</code> message doesn't appear at all. What is wrong in this code?</p>