Select some entities from row in ui-grid - angularjs

Question

I have in my grid sometimes few columns, I hide some that only two are visible. I want to select rows only with these two entities(visible) and pass them to array. In this example Date and Result. Is there specific method to do this? Because when I use
vm.chartData.push($scope.gridApi.selection.getSelectedRows()) in chartData array I have got all entities.
This is my controller code.
(function () { "use strict";
angular.module("app")
.controller("grid", grid);
function grid($scope) {
var vm = this;
vm.chartData = [];
$scope.gridOptions =
{
enableGridMenu: true,
enableSorting: true,
enableRowSelection: true,
selectionRowHeaderWidth: 35,
enableSelectAll: true,
multiSelect: true,
columnDefs: [
{ name: 'Trial', field: 'Trial' },
{ name: 'Date', field: 'Date', type: "date", cellFilter: "date:'dd-MM-yyyy HH:mm'" },
{ name: 'Result', field: 'Result'}
],
data: [
//example of row entities
{
"Trial": "Weight",
"Date": "2015-02-03T05:49:54.850Z",
"Result": 60
}
]
};
$scope.pushAll = function () {
//this line returns all three entities
vm.chartData.push($scope.gridApi.selection.getSelectedRows());
};
$scope.gridOptions.onRegisterApi = function (gridApi) {
$scope.gridApi = gridApi;
};
}