How to format and add isPrimaryKey property to auto generated columns?

    function dataBound(args) {
                    for (var column = 0; column < this.model.columns.length; column++) {
                        if (this.model.columns[column]["type"] == "number") //Align based on column field
                            this.model.columns[column].textAlign = "right";                        
                        if (this.model.columns[column]["field"] == "EmployeeID") //Adding primary key based on field
                            this.model.columns[column].isPrimaryKey = true;
                        else if (this.model.columns[column]["field"] == "Freight") //Formating based on field
                            this.model.columns[column].format = "{0:C}";
                            
                    }
                    this.refreshContent(true); //Reflect the changes in grid
                }

<div id="Grid"></div>
<script type="text/javascript">
    $(function () {// Document is ready.        
        $("#Grid").ejGrid({
            dataSource: data, // the datasource "data" is referred from jsondata.min.js            
                      dataBound: "dataBound",
    });
    });
</script>

[In View]
@(Html.EJ().Grid<object>("Grid")
        .Datasource((IEnumerable<object>)ViewBag.data)         
        .ClientSideEvents(eve=>eve.DataBound("dataBound"))
 )
[Controller]
namespace EJGrid.Controllers
{
    public class HomeController : Controller
    {
        public ActionResult Index()
        {
            var DataSource = OrderRepository.GetAllRecords();
            ViewBag.data = DataSource;
            return View();
        }        
    }
}

[aspx]
<ej:Grid ID="OrdersGrid" runat="server" >  
            <ClientSideEvents DataBound="dataBound" />              
</ej:Grid>  
[CS]
public partial class _Default : Page
{    
    protected void Page_Load(object sender, EventArgs e)
    {
            this.OrdersGrid.DataSource = new NorthwindDataContext().Orders;
            this.OrdersGrid.DataBind();
    }
}