pagination doesn't work with custom data from json file

I am using custom data from .json file and want to paginate the data but all data comes in single page ; why so? below are my code

 $http.get('app/user_keys.json').success(function(data) {
            vm.data = data;
            vm.tableParams = new NgTableParams({ page: 1, count: 2 }, {
                    total: vm.data.length,
                    getData: function (params) {
                        console.log(vm.data.length);
                        var deferred = $q.defer();
                        var orderedData = params.sorting() ? $filter('orderBy')(vm.data, params.orderBy()) : vm.data;
                        deferred.resolve(orderedData.slice((params.page() - 1) * params.count(),  params.page() * params.count()));
                    }
                });
        });

<table ng-table="vm.tableParams" class="table table-striped" >
                    <colgroup>
                          <col width="5%"/>
                          <col width="30%"/>
                          <col width="50%"/>
                          <col width="15%"/>
                    </colgroup>
                    <tr ng-repeat="row in vm.data | filter: searchText  track by $index">
                        <td header="'headerCheckbox.html'">
                        <input type="checkbox" value="row._id" ng-model="vm.checkboxes.items[row._id]" ></td>
                        <td data-title="'ID'">{{ row.index }}</td>
                        <td data-title="'Cloud Location'">{{ row.location }}</td>
                        <td data-title="'Action'"><i class="fa fa-trash"></i></td>
                    </tr>
                </table>

[miparnisari]

Ok I fixed it, it’s because dataOptions may be undefined. So the code should be

 if (settings.dataOptions && !settings.dataOptions.applyPaging) {
   return ngTableDefaultGetData(result, params);
 }

[fsm3xpert]

I’ve same problem, when paging on group data. So, i add these lines at the end on getGroups function.

if (!settings.dataOptions.applyPaging) {
    return ngTableDefaultGetData(result, params);
}
return ngTableDefaultGetData.applyPaging(result, params);

The pagination working on either used default or custom.