c# - Group By List

Question

I have this class:

public class Item 
{
    public virtual int32 Id { get; set; }
    public virtual Previa Previa { get; set; }
    public virtual Product Product { get; set; }
    public virtual Int32 Quantity { get; set; }
    public virtual Decimal Price { get; set; }
    public virtual Decimal Total { get; set; }
}

And now i need to a query to find every Items in database, group by Products, with the sum of Quantity and Total. For find every Items, i use:

public List<Item> FindItem(int IdProduct = 0)
{
    var retorno = (from c in Session.Query<Item>()
                   select c);

    if (IdProduto > 0)
        retorno = retorno.Where(x => x.Product.Id == IdProduct)

    return retorno.ToList<Item>();
}

But I don't know how to group these items. Could someone please help me?

Answer 1

您的问题还很不清楚，但听起来您想要一个查询，例如：

var query = from item in Session.Query<Item>()
            group item by item.Product into g
            select new {
                Product = g.Key,
                Quantity = g.Sum(item => item.Quantity),
                Total = g.Sum(item => item.Total)
            };

然后你如何把它传回去是另一回事 - 你几乎肯定不想要一个List<Item>...