c# - Optimizing Repository’s SubmitChanges Method

Question

I have following repository. I have a mapping between LINQ 2 SQL generated classes and domain objects using a factory.

The following code will work; but I am seeing two potential issues

1) It is using a SELECT query before update statement.

2) It need to update all the columns (not only the changed column). This is because we don’t know what all columns got changed in the domain object.

How to overcome these shortcomings?

Note: There can be scenarios (like triggers) which gets executed based on specific column update. So I cannot update a column unnecessarily.

REFERENCE:

1. LINQ to SQL: Updating without Refresh when “UpdateCheck = Never”

2. http://www.sqlteam.com/forums/topic.asp?TOPIC_ID=113917

CODE

namespace RepositoryLayer
{
public interface ILijosBankRepository
{      
    void SubmitChangesForEntity();
}

public class LijosSimpleBankRepository : ILijosBankRepository
{

    private IBankAccountFactory bankFactory = new MySimpleBankAccountFactory();
    public System.Data.Linq.DataContext Context
    {
        get;
        set;
    }


    public virtual void SubmitChangesForEntity(DomainEntitiesForBank.IBankAccount iBankAcc)
    {
        //Does not get help from automated change tracking (due to mapping)

        //Selecting the required entity
        DBML_Project.BankAccount tableEntity = Context.GetTable<DBML_Project.BankAccount>().SingleOrDefault(p => p.BankAccountID == iBankAcc.BankAccountID);

        if (tableEntity != null)
        {
            //Setting all the values to updates (except primary key)
            tableEntity.Status = iBankAcc.AccountStatus;

            //Type Checking
            if (iBankAcc is DomainEntitiesForBank.FixedBankAccount)
            {
                tableEntity.AccountType = "Fixed";
            }

            if (iBankAcc is DomainEntitiesForBank.SavingsBankAccount)
            {
                tableEntity.AccountType = "Savings";
            }

            Context.SubmitChanges();
        }
    }
}

}

namespace DomainEntitiesForBank
{

public interface IBankAccount
{
    int BankAccountID { get; set; }
    double Balance { get; set; }
    string AccountStatus { get; set; }
    void FreezeAccount();

}

public class FixedBankAccount : IBankAccount
{

    public int BankAccountID { get; set; }
    public string AccountStatus { get; set; }
    public double Balance { get; set; }

    public void FreezeAccount()
    {
        AccountStatus = "Frozen";
    }
}


}

Answer 1

This isn't really a DDD question; from what I can tell you are asking:

Use linq to generate direct update without select

Where the accepted answer was no its not possible, but theres a higher voted answer that suggests you can attach an object to your context to initiate the change tracking of the data context.

Your second point about disabling triggers has been answered here and here. But as others have commented do you really need the triggers? Should you not be controlling these updates in code?

In general I think you're looking at premature optimization. You're using an ORM and as part of that you're trusting in L2S to make the database plumbing decisions for you. But remember where appropriate you can use stored procedures execute specific your SQL.