how to get mulit-relative attribute

i have three models A,B,C. A belongs to B,B belongs to C.How to get C’s attribute in A’s gridview?

in the item list:


   'label'=>'Attribute of C',



This works if you have the relation B0 in A and C0 in B that returns the B and C models respectively.

thx,it works and i want to know how to set filters,i means how to modify the search() function