Form input validation with angular js

Question

I am trying to disable the button if all inputs are not populated, If they are populated then the button is enabled.

I am also trying to print text under the input if no text is present in the input field, but only if user clicks on the disabled button.

My question

How do I alter my code to enable my button once text is present in all the input fields and if they are not and the user clicks on the disabled button show

<div ng-if="!myForm.Lname.$invalid">
    <p>This field is required</p>
</div>

but only if text is not present in the input fields.

FULL CODE

<div class="form-group">
    <label for="first-name">First Name*</label>
    <input type="text" class="form-control" name="Fname" placeholder="Enter first name" ng-model="formData.Fname"  ng-required="true">
     <div ng-if="!myForm.Fname.$invalid">
        <p>This field is required</p>
    </div>
</div>

<div class="form-group">
    <label for="last-name">Last Name*</label>
    <input type="text" class="form-control" name="Lname" placeholder="Enter last name" ng-model="formData.Lname" ng-required="true">
    <div ng-if="!myForm.Lname.$invalid">
        <p>This field is required</p>
    </div>
</div>

<div class="form-group">
    <label for="email">Email*</label>
    <input type="email" class="form-control" name="email" placeholder="Enter a valid email address" ng-model="formData.email" ng-required="true">
</div>

<div class="form-group row">
    <div class="col-xs-6 col-xs-offset-3">

        <button ui-sref="form.select" class="btn btn-block btn-info" ng-disabled="!myForm.Fname.$valid">
            Next Section <span class="glyphicon glyphicon-circle-arrow-right"></span>
        </button>

    </div>
</div>

Answer 1

You can do this by creating your own directive. I hope this will help you.

Here's a demo on Jsfiddle

HTML:

<div ng-app="sampleapp">
<div ng-controller="samplecontoller" ng-init="showData()">
 <form name="form" disable-btn ng-submit="submitForm()">
   <div>
   <label>First Name:</label>
     <input type="text" placeholder="First Name" ng-model="model.name" required>
  </div>
  <div>
    <label>Last Name:</label>
    <input type="text"placeholder="Last Name"  ng-model="model.lname" required>
   </div>
  <div>
    <button class="btn btn-primary" type="submit">Submit</button>
  </div>
</form>  
</div>