title: Angular Grid ag-grid columnDefs Dynamically change
body: <p>I have a problem about <code>columnDefs</code> change dynamically. Here is my gridOptions:</p>
  <pre><code>$scope.gridOptions = {
    columnDefs: [],
    enableFilter: true,
    rowData: null,
    rowSelection: 'multiple',
    rowDeselection: true
  };
  </code></pre>
  <p>And when I retrieve data from server:</p>
  <pre><code>$scope.customColumns = [];
  
  $http.post('/Home/GetProducts', { tableName: 'TABLE_PRODUCT' }).success(function (data) {
      angular.forEach(data.Columns, function (c) {
          $scope.customColumns.push(
              {
                  headerName: c.Name,
                  field: c.Value,
                  width: c.Width
              }
          );
      });
  
      $scope.gridOptions.columnDefs = $scope.customColumns;
  
      $scope.gridOptions.rowData = data.Products;
      $scope.gridOptions.api.onNewRows();
  }).error(function () {
  
  });
  </code></pre>
  <p><strong>Note: here c is column object which comes from server.</strong></p>
  <p>When dynamically generating columns and assigning it to $scope.gridOptions.columnDefs there is blank grid but <code>$scope.customColumns</code> array is filled with right generated column objects. Please help me is this bug or I am doing something wrong?</p>