<input type="text" ng-model="search" ng-change="test()">

$scope.test=function()
{
  var val=$scope.search;
  alert(val);
}

$scope.search=33;
$scope.test=function()
{
      var val=$scope.search;
      alert(val);
 }

<input type="text" ng-model="search.text" ng-change="test()">

$scope.search={'text':''};
$scope.test=function()
{
  var val=$scope.search.text;
  alert(val);
}