asp.net mvc 4 - 无法将类型"System.Linq.IQueryable<AnonymousType#1>"隐式转换为"System.Collections.Generic

Question

当我尝试连接三个表ProductPhoto, Product和ProductProductPhoto时，我遇到了这个问题。我试了很多案例，但都没有成功。有人能帮我脱下来吗?谢谢你的回复!

private IEnumerable<SubCateViewModel> GetSubProduct()
            {
                var context = new AdvenDBEntities();
                var subcate = (from a in context.ProductPhotoes
                              join b in context.ProductProductPhotoes on a.ProductPhotoID equals b.ProductPhotoID
                              join c in context.Products on b.ProductID equals c.ProductID
                              join d in context.ProductSubcategories on c.ProductSubcategoryID equals d.ProductSubcategoryID
                              select new
                              {
                                  a.ProductPhotoID,
                                  a.ThumbnailPhotoFileName,
                                  c.ProductID,
                                  c.Name,
                                  d.NameofBike,
                                  d.isSelected,
                              }).AsQueryable();
                         return subcate;
            }

Answer 1

试试下面的代码…

private IEnumerable<SubCateViewModel> GetSubProduct()
                {
                    var context = new AdvenDBEntities();
                    var subcate = (from a in context.ProductPhotoes
                                  join b in context.ProductProductPhotoes on a.ProductPhotoID equals b.ProductPhotoID
                                  join c in context.Products on b.ProductID equals c.ProductID
                                  join d in context.ProductSubcategories on c.ProductSubcategoryID equals d.ProductSubcategoryID
                                  select new SubCateViewModel
                                  {
                                     ProductPhotoID =  a.ProductPhotoID,
                                      ThumbnailPhotoFileName = a.ThumbnailPhotoFileName,
                                     ProductID = c.ProductID,
                                      Name = c.Name,
                                      NameofBike = d.NameofBike,
                                      isSelected = d.isSelected,
                                  });
                             return subcate.AsEnumerable();
                }

Answer 2

问题是匿名类型的列表不能转换为SubCateViewModel的列表。

你为什么要使用匿名类型呢?只需在查询中创建一个新的SubCateViewModel实例(选择SubCateViewModel而不是匿名类型)。

在LINQ中使用:

代替匿名类型

select new SubCateViewModel 
{
// Set class variables here...
}