I posted this question slightly differently on a different forum, and got the following solution.
Basically I return the data as an IQueryable from the DAL which has already been forced to execute using ToList(). This means that I am running my sorting and paging against an object which consists of data from the DB and DLL. This also allows Scott's dynamic sorting to take place.
The BLL then performs OrderBy(), Skip() and Take() on the returned IQueryable and then returns this as a List to my GridView.
It works fine, but I am slightly bemused that we are perfoming IQueryable to List to IQueryable to List again.
1) Get the results from the database as an IQueryable:
public class DAL
{
public IQueryable<Customer> GetCustomers()
{
Entities entities = new Entities();
var customers = (from c in entities.Customers
select c);
//CustomerID is a field in the Customer table
return customers.ToList().AsQueryable();
}
}
2) Pull the results into my business layer:
public class BLL
{
public List<Customer> GetCustomers(intint startRowIndex, int maximumRows, string sortParameter)
{
DAL customersDAL = new DAL();
return customersDAL.GetCustomers().OrderBy(sortParameter).Skip(startRowIndex).Take(maximumRows).ToList();
}
}
Here is the link to the other thread.
Hope this helps others!