Question

We have a site using Unity and IUnitOfWork for our EF context. Until now we’ve only been using a single EF Context so this is the one mapped in Unity config. This has all been handled through constructor injection and this is something we’d like to maintain for consistency.

We’ve now introduced another EF Context for our PaymentController that is used within the site but Unity config currently only allows us to create one type for IUnitOfWork.

I know that I can create a new <register/> element for the new context with a distinct name attribute but how do I implement this within the controller constructor to use the one named payments?

  <register type="IUnitOfWork" mapTo="FirstContext" />
  <register type="IUnitOfWork" mapTo="PaymentsContext" name="payments"/>

  public class PaymentController()
  {
    public PaymentController(IUnitOfWork unitOfWork) 
    {
        //How to I tell unity that this needs to be a payments
        _unitOfWork = unitOfWork;
    }
  }

Many Thanks

Answer 1

When the FirstContext and PaymentsContext have each an unique set of entities (for instance, each connect to a different database) it is worth wild to explicitly define this in code. One way of doing this is by specifying a factory for each unit of work:

public interface IFirstContextFactory
{
    IUnitOfWork CreateNew();
}

public interface IPaymentContextFactory
{
    IUnitOfWork CreateNew();
}

public class PaymentController()
{
   public PaymentController(PaymentContextFactory paymentContextFactory)
   {
      //How to I tell unity that this needs to be a payments
      this.paymentContextFactory = paymentContextFactory;
   }

   public void DoSomething()
   {
      using (var context = this.paymentContextFactory.CreateNew())
      {
         // Do something useful

          context.Commit();
      }
   }
}

Not only makes this your dependencies very clear (because you know what type of context the code is dealing with), but it also simplifies the DI configuration, because you won’t need any named registrations.