title: Alert controller input box validation
body: <p>How to validate and show error for Input in Alert Controller in Ionic 2 or 3</p>
  
  <pre><code>let prompt = Alert.create({
        title: 'Alert input validation',
        message: "How can I validate below input field?",
        inputs: [ 
          {
            name: 'email',
            placeholder: 'email'
          },
        ],
        buttons: [
          {
            text: 'Save',
            handler: data =&gt; {
                          let validateObj = this.validateEmail(data);
                          if (!validateObj.isValid) {
                              alert(validateObj.message);
                              return false;
                          } else {
                              //make HTTP call
                          }
                      }
          }
        ]
      });
  </code></pre>
  
  <p>Some one already updated alertcontroller and did pull request for Ionic team. i think Ionic team planning implement this in future.
  <a href="https://github.com/ionic-team/ionic/pull/12541" rel="noreferrer">https://github.com/ionic-team/ionic/pull/12541</a></p>
  
  <p>I need some work around for this validation feature.</p>
  
  <p>plnkr
  <a href="http://plnkr.co/edit/IBonfBJngky0h8UtMwMD?p=preview" rel="noreferrer">http://plnkr.co/edit/IBonfBJngky0h8UtMwMD?p=preview</a></p>
  
  <p>Appreciate your help.</p>