Question

I have a layered application with the following projects:

• DAL (using EntityFramework with repositories)
• DAL.Model (contains the entities, and is referenced by all the others)
• Services
• UI (in wpf)

The base repository looks like this:

public abstract class RepositoryBase<T> where T : class
{
    private readonly MyContext context;
    private readonly IDbSet<T> dbSet;

    protected RepositoryBase(MyContext dataContext)
    {
        context = dataContext;
        dbSet = context.Set<T>();
    }

    protected MyContext Context
    {
        get { return context; }
    }

    **And a series of virtual methods for Add, Delete, etc.
}

All repositories extend this one, such as:

public class MarketRepository : RepositoryBase<Market>
{
    public MarketRepository(MyContext dataContext) : base(dataContext)
    {

    }

    public IEnumerable<Market> GetAllMarkets()
    {
        return this.Context.Markets.ToList<Market>();
    }
}

The services look like this:

public class MarketService
{
    IMarketRepository _marketRepository;

    public MarketService(IMarketRepository marketRepository)
    {
        _marketRepository = marketRepository;
    }

    public IEnumerable<Market> GetAllMarkets()
    {
        return _marketRepository.GetAllMarkets();
    }
}

What I would like to achieve is that the UI layer would only have a reference to the Services layer, the Services layer only with the DAL layer (and all of them to Model, where the entities live) using DI (right now I’m using Unity).

The problem is, in my container in the UI I only want to do this

unity.RegisterType<IMarketService, MarketService>();

and not have to do it as well for the repositories, because then the UI layer would have a dependency on the DAL layer.

I thought about adding a parameterless constructor to the Service classes, like:

public MarketService() : this(new MarketRepository(*What would I put here?)) { }

but then I’m loosing the abstraction that the interface gives, and also I don’t know what to do with the MyContext that the repository needs as a parameter; if I pass a new one, then I need to reference the DAL.

Should I change my repositories to create a new MyContext in the constructor, rather than getting it as a parameter?

How can I refactor my architecture to make it work properly and with minimal dependencies?

Answer 1

Well, I belive it is up to the bootstrapper to configure dependencies, in the higher level of the application. As it is usually the UI project, if it needs to reference other assemblies, so be it. If you do not like your UI project managing that, than create a bootstrapper project responsable for getting your app running and separete your UI classes in another one.