(app.js)

angular.module('myApp', ['restangular'])
.controller('Ctrl', function($scope, Restangular) {
  Restangular
  .one('widget', 4)
  // get() will return a promise for the GET request
  .get()
  .then(
    function(data) {
      // consume response data in success handler
      $scope.status = 'One widget success!';
    },
    function(response) {
      // consume response message in error handler
      $scope.status = 'One widget failure!';
    }
  );
  
  // generally, the API mapping is stored in a variable,
  // and the promise-returning method will be invoked as needed
  var widgets = Restangular.all('widgets');
  
  // create the request promise
  widgets.getList()
  .then(function(widgets) {
    // success handler
    ...