Ng-model does not update controller value

Probably silly question, but I have my html form with simple input and button:

<input type="text" ng-model="searchText" />
<button ng-click="check()">Check!</button>
{{ searchText }}

Then in the controller (template and controller are called from routeProvider):

$scope.check = function () {
    console.log($scope.searchText);
}

Why do I see the view updated correctly but undefined in the console when clicking the button?

Thanks!

Update: Seems like I have actually solved that issue (before had to come up with some workarounds) with: Only had to change my property name from searchText to search.text, then define empty $scope.search = {}; object in the controller and voila... Have no idea why it's working though ;]

Controller as version (recommended)

Here the template

<div ng-app="example" ng-controller="myController as $ctrl">
    <input type="text" ng-model="$ctrl.searchText" />
    <button ng-click="$ctrl.check()">Check!</button>
    {{ $ctrl.searchText }}
</div>

The JS

angular.module('example', [])
  .controller('myController', function() {
    var vm = this;
    vm.check = function () {
      console.log(vm.searchText);
    };
  });

An example: http://codepen.io/Damax/pen/rjawoO

The best will be to use component with Angular 2.x or Angular 1.5 or upper

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Old way (NOT recommended)

This is NOT recommended because a string is a primitive, highly recommended to use an object instead

Try this in your markup

<input type="text" ng-model="searchText" />
<button ng-click="check(searchText)">Check!</button>
{{ searchText }}

and this in your controller

$scope.check = function (searchText) {
    console.log(searchText);
}