Question

I have a problem in architecting my application.

I have the following structure with only important aspects shown.

namespace Domain
{
   public class Invoice
   {
     //properties
   }

public class InvoiceRepository
{
   public Linq2SqlContext context = new Linq2SqlContext();

   public IQueryable<Invoice> GetInvoices()
   {
              var query = from inv in _dbctx.Invoices orderby inv.invInvoiceDate descending select GetInvoice(inv) ;

            return query;

   }
}
public class InvoiceService()
{
   public InvoiceRepository _repository = new InvoiceRepositroy();
   public IQueryable<Invoice> GetInvoices()
   {
      return _repository.GetInvoices();
   }   

}
}

namespace MyApp
{
   public class UI
   {
      public InvoiceService _service =  new InvoiceService();
      public void FilterInvoices()
      {
            var query =
                   (
                     from i in _service.GetInvoices()
                     from s in _service.GetStatuses()
                     where i.ProjectID == _projectid &&
                           s.ID == i.Status
                     select new
                     {
                         InvoiceID = i.ID,
                         DocumentTotal = i.TotalDue.ToString(),
                         Created = i.Created,
                         WeekEnding = i.WeekEnding,
                         Status = s.staStatus
                     }
                   ).Skip(_pageIndex * _pageSize).Take(_pageSize);

      }

   }
{

So I want to return IQueryable from my service so I can
filter from client code. But the problem I’m coming up with
is the FilterInvoices method errors with “No supported
translation to sql” because of the GetInvoice method
which is iused to return an Invoice entity (this is
a layer on top op the LInq2 sql layer) and not an Linq2sql Invoice entity.

So how do I return a IQueryable from my service with this structure??
Also how do I sort and return a IQureyable in repository GetInvoices.

Hope this makes sense.

Malcolm

Answer 1

linq2sql thinks GetInvoice (within GetInvoices) is a stored procedure. One way around it

var query = from inv in _dbctx.Invoices orderby inv.invInvoiceDate descending select inv ;

though that would pass back the objects generated by your datacontext. If you wanted to populated custom objects you could iterated over the collection creating your custom Invoice objects and populating them.

foreach(var inv in query) { somelist.Add(new MyCustomInvoince() { id = inv.id ... }

EDIT: The above will return a list. Use the following to return IQueryable

return from item in query
    select GetInvoice(item);

The difference is at this stage your are using Linq2Objects, and that provider will know how to call GetInvoice