Getting radio button value when button is clicked is not working angularjs

Problem

I am new in angularjs.I want to fetch the radio button value when user click a button,but my bad luck its not working.Here is the code

<label class="item item-radio">
    <input type="radio" name="group" ng-model="user.answer" value="{{questions.quiz_ans_opt1}}">
    <div class="item-content item-body">a) {{questions.quiz_ans_opt1}}</div><i class="radio-icon ion-checkmark"></i>
</label>
<label class="item item-radio item-body">
    <input type="radio" name="group" ng-model="user.answer" value="{{questions.quiz_ans_opt2}}">
    <div class="item-content item-body">b) {{questions.quiz_ans_opt2}}</div><i class="radio-icon ion-checkmark"></i>
</label>
<button class="button button-balanced button-block" ng-click="submitAnswer(user)">Submit</button>

Here is controller

$scope.submitAnswer = function(user) {
    //it output undefined error
    alert(user);
}

Also i want to disable the button until a radio button is checked,how can i achive this?

Problem courtesy of: Blessan Kurien

Solution

Please have a look at this,

Try this,

In html,

<body ng-controller="MainCtrl">
  <p>Hello {{name}}!</p>
  <input type="radio" ng-model="user.answer" ng-value="'option a'">
  <label>option a</label>
  <br>
  <input type="radio" ng-model="user.answer" ng-value="'option b'">
  <label>option b</label>
  <br>
  <input type="radio" ng-model="user.answer" ng-value="'option c'">
  <label>option c</label>
  <br>
  <input type="radio" ng-model="user.answer" ng-value="'option d'">
  <label>option d</label>
  <br>
  <button ng-disabled="!user.answer" ng-click="submitAnswer(user)">Submit</button>
</body>

In app.js,

var app = angular.module('plunker', []);

app.controller('MainCtrl', function($scope) {
  $scope.name = 'World';
  $scope.submitAnswer=function(user){

    alert(user.answer);

  }
});

Here is the plunker demo for the same

Solution courtesy of: Mahe Sirius

Discussion

Though a bit late, i would like to post a second approach, since you are using Ionic-Framework.

If you at all have a dynamic number of radio button options, that are being driven by backend data [Even if you have a static radio button set, you can convert it to the formal], Then you should instead use Ionic's Radio Buttons :

I.E, In your HTML :

<ion-radio ng-repeat="user in userAnswers"
           ng-value="user.answer"
           ng-model="finalAnswer">
  {{ item.text }}
</ion-radio>

And in your controller :

$scope.userAnswers = [
    { text: "Backbone", answer: "bb" },
    { text: "Angular", answer: "ng" },
    { text: "Ember", answer: "em" },
    { text: "Knockout", answer: "ko" }
  ];

  $scope.finalAnswer = 'ng';

More Details can be found in the official documentation and the CodePen Demo

Discussion courtesy of: Manish Kr. Shukla

This post really helped me out. I ended up changing all my radio button ng-click events to ng-change. Hope this helps.

AngularJS - Trigger when radio button is selected

Discussion courtesy of: Jason Spence

This recipe can be found in it's original form on Stack Over Flow.