按类别返回列表产品组时出错:
错误1无法隐式转换类型'System.Linq.IQueryable>'到'System.Linq.IQueryable'。存在显式转换(您是否错过了演员?)
我的代码:
public IQueryable<GroupModel> GetAll()
{
List<Category> listCategories = new List<Category>
{
new Category {Id = 1, CateName = "SmartPhone", Description = "aaaaaa"},
new Category {Id = 2, CateName = "Laptop", Description = "bbbb"},
new Category {Id = 3, CateName = "Desktop", Description = "ccccc"},
};
List<Product> listProducts = new List<Product>
{
new Product {Id = 1, ProdName = "Lumia 720", CategoryId = 1, ColorId = 2},
new Product {Id = 2, ProdName = "PC HP", CategoryId = 3, ColorId = 1},
new Product {Id = 3, ProdName = "PC Dell", CategoryId = 3, ColorId = 1},
new Product {Id = 4, ProdName = "Laptop Lenovo", CategoryId = 2, ColorId = 2},
new Product {Id = 5, ProdName = "Lumia 920", CategoryId = 1, ColorId = 2},
new Product {Id = 6, ProdName = "Laptop Dell", CategoryId = 2, ColorId = 3},
new Product {Id = 7, ProdName = "Laptop HP", CategoryId = 2, ColorId = 3},
new Product {Id = 7, ProdName = "Lumia 1020", CategoryId = 1, ColorId = 1}
};
List<Color> listColors = new List<Color>
{
new Color {ColorId = 1, ColorName = "Blue"},
new Color {ColorId = 2, ColorName = "Yellow"},
new Color {ColorId = 3, ColorName = "Red"}
};
var query = (from p in listProducts
join co in listColors on p.ColorId equals co.ColorId
join c in listCategories on p.CategoryId equals c.Id into e
from j in e.DefaultIfEmpty()
select new GroupModel
{
CategoryId = j.Id,
CategoryName = j.CateName,
ProductId = p.Id,
ProductName = p.ProdName,
ColorId = co.ColorId,
ColorName = co.ColorName
}).ToList().GroupBy(x => x.CategoryName);
return query.AsQueryable();
}
答案 0 :(得分:1)
尝试关注最后一句话
return query.SelectMany(x=>x).AsQueryable();
答案 1 :(得分:1)
您的linq查询返回IGrouping<string,GroupViewModel>
而不是IQueryable<GroupViewModel>
。将您的方法签名更改为:
public IQueryable<IGrouping<string,GroupViewModel>> GetAll()
{
var query = (from p in listProducts
.......................
.......................
return query.AsQueryable<IGrouping<string,GroupViewModel>>();
}