Complex GROUP BY on DataTable

Question

I have a complex entity CostPageDTOas shown below:

public class CostPageDTO
{
    public string CostPageNumber { get; set; }
    public string D         


        

Answer 1

I'm assuming your database query returns a join between CostPage and Item. If that's the case, first you have to group your rows to get the values for CostPage, after that project to your DTO type. I really doubt that you'll see much benefit in parallelizing the code.

Your code should look roughly like this:

costPages = table.AsEnumerable().GroupBy(dr=> new 
            {
                CostPageNumber  = dr[0].ToString(),
                Description = dr[1].ToString(),
                OrderType = Convert.ToChar(dr[2].ToString()),
                VendorName = dr[3].ToString()
            })
            .Select(x => new CostPageDTO(){
                CostPageNumber = x.Key.CostPageNumber,
                Description = x.Key.Description,
                OrderType = x.Key.OrderType,
                VendorName = x.Key.VendorName,
                Items = x.Select(dr=> new ItemDTO{
                    //ItemDTO mapping goes here
                    ItemID=dr[Constants.SearchPage.ITMID].ToString()
                }).ToList()
            }).ToList();