group filed kendo grid with type object

问题

I have similar example to this grid http://jsfiddle.net/Sbb5Z/478/

I want to apply grouping on category field. I got an error. because category filed type is object. How can I specify the grouping filter field.

I tried this but it did not work

 groupable: {    
            field:"Category.CategoryName",
        } 

Any ideas ??

来源：https://stackoverflow.com/questions/17547302/group-filed-kendo-grid-with-type-object