Question

My system has this pattern DAO->Objects->facade->View

so i have a DAO to query database, and instantiate objects, this objects has only attributes (just a container / entity), i want to use LINQ in DAO part, but i dont realize how to pass my objects becouse LINQ generate 1-per table.

namespace ykpObjects.Objects
{
public class Customer
    {
        public string name { get; set; }
        public Cidade()
        {
            cidadeID = 0;
        }
    }
}

---

namespace ykpData.Components.MSSQL
{

    public class CustomerDC : DataComponentCM, ICustomerDC
    {

        Customer ICustomerDC.RecuperaPorID(int CustomerID)
        {
            Customer Customer = new Customer();

            using (MDDataContext omd = new MDDataContext(base.PreencherConexao()))
            {
                sp_mkp_Customer_SelectByIDResult result = omd.sp_mkp_Customer_SelectByID(CustomerID).SingleOrDefault();
                if (result == null)
                    return null;

                Customer.name = result.name;


                return Customer;
            }
        }
    }
}

I use DAO to call sprocs, so i get sproc results and instanciate a object of Customer for exemple, and pass this to control, now i want to change to linq but i dont wanna change all object structure to minimalize the impact.

Any advice ?

Answer 1

I’m not exactly sure what you are talking about with your current setup, but I think you’re asking how to re-use the objects you currently have with Linq to SQL, rather than generating new ones from a dbml file. Am I right?

If so, you have a few options. You can use attributes to decorate your existing objects so that you can populate them with L2S, or you can create mapping files.

Some info here: http://www.sidarok.com/web/blog/content/2008/10/14/achieving-poco-s-in-linq-to-sql.html

I use Linq to SQL with attributes to achieve a “code first” solution, here’s an example class:

[Table(Name = "Countries")]    
public class Country
{
    [Column(IsPrimaryKey = true, IsDbGenerated = true, AutoSync = AutoSync.OnInsert)]
    public int CountryId { get; set; }

    [Column]
    public string iso2 { get; set; }

    [Column]
    public string iso3 { get; set; }

    [Column]
    public string name_en { get; set; }
}

To work with this object:

var context = new DataContext(ConnectionString);
var data = context.GetTable<Country>().Where(c => c.CountryId == 1);