使用 linq C# 返回列表值

Question

Actually I want to return the data from different lists based on Date. When i'm using this i'm getting data upto @Var result but i'm unnable to return the data. The issue with this is i'm getting error @return result. I want to return the data @return result. I'm using Linq C#. Can anyone help me out?

    public List<CustomerWiseMonthlySalesReportDetails> GetAllCustomerWiseMonthlySalesReportCustomer()
    {
        var cbsalesreeport = (from cb in db.cashbilldescriptions
                              join c in db.cashbills on cb.CashbillId equals c.CashbillId
                              join p in db.products on cb.ProductId equals p.ProductId


                              select new
                              {
                                  Productamount = cb.Productamount,
                                  ProductName = p.ProductDescription,
                                  CashbillDate = c.Date
                              }).AsEnumerable().Select(x => new ASZ.AmoghGases.Model.CustomerWiseMonthlySalesReportDetails
                            {

                                Productdescription = x.ProductName,
                                Alldates = x.CashbillDate,
                                TotalAmount = x.Productamount
                            }).ToList();

        var invsalesreeport = (from inv in db.invoices
                               join invd in db.invoicedeliverychallans on inv.InvoiceId equals invd.InvoiceId
                               select new
                               {
                                   Productamount = invd.Total,
                                   ProductName = invd.Productdescription,
                                   InvoiceDate = inv.Date
                               }).AsEnumerable().Select(x => new ASZ.AmoghGases.Model.CustomerWiseMonthlySalesReportDetails
                            {

                                Productdescription = x.ProductName,
                                Alldates = x.InvoiceDate,
                                TotalAmount = x.Productamount
                            }).ToList();
        var abc = cbsalesreeport.Union(invsalesreeport).ToList();

        var result = (from i in abc
                 group i by new { Date = i.Alldates.ToString("MMM"), Product = i.Productdescription } into grp
                 select new { Month = grp.Key, Total = grp.Sum(i => i.TotalAmount) });

        **return result;**

    }

Answer 1

You can either convert your result to a List before returning it using return result.ToList() or make your method return an IEnumerable<CustomerWiseMonthlySalesReportDetails> instead of List .

As your result is an enumeration of anonymous types you have to convert them to your CustomerWiseMonthlySalesReportDetails -type first:

select new CustomerWiseMonthlySalesReportDetails{ Month = grp.Key, Total = grp.Sum(i => i.TotalAmount) });

Assuming your type has exactly the members returned by the select.

EDIT: So your code should look like this:

var result = (from i in abc
             group i by new { Date = i.Alldates.ToString("MMM"), Product = i.Productdescription } into grp
             select new CustomerWiseMonthlySalesReportDetails{ Month = grp.Key, Total = grp.Sum(i => i.TotalAmount) });

return result.ToList();

Answer 2

You can assume Alldates property if is date of one of groups that month of date is in right place:

var result = (from i in abc
   group i by new { Date = i.Alldates.ToString("MMM"), Product = i.Productdescription } 
   into grp
   select new CustomerWiseMonthlySalesReportDetails{ 
          Productdescription = grp.Key.Product, 
          TotalAmount = grp.Sum(i => i.TotalAmount), 
          Alldates =grp.First(i=>i.Alldates ) })
   .ToList();