您需要得到LINQ来填充它，
使用类似
VAR的查询=从产品repo.All（产品）
            加入categoryItem在repo.All（类别）
            在product.CategoryId等于categoryItem.Id
            选择新{
              ID = product.ID，
              名称= product.name，
              说明= product.description，
              的categoryId = product.CategoryId
              类别= categoryItem
           };

you need to get linq to populate it,
using something like
var query = from product in repo.All(Product)
join categoryItem in repo.All(Category)
on product.CategoryId equals categoryItem.Id
select new {
ID = product.ID,
name = product.name,
description = product.description,
categoryId= product.CategoryId
category = categoryItem
};