Dependency Injection

Question

We are creating an application for the Windows desktop (and not on the website) and are trying to find the best way to implement the repository and UnitOfWork template.

In a typical Asp.Net Mvc application, your repositories are entered by the data context, repositories are introduced to the services, and finally, services are introduced to the controllers, and everything is fine, if you do not get into any exception, you make changes.

In windows / wpf applications, it is not recommended to use a single datacontext ( Oren has a message on this in MSDN), so we decided to create a data context in the presenter. We use Linq2SQl, and we have two different databases for working with presentation.

I currently have the following implementation

public interface IRepository<T> where T : class
    {
        IEnumerable<T> Find(Expression<Func<T, bool>> where);
        T Single(Expression<Func<T, bool>> where);
        ...
     }

public class Repository<T> : IRepository<T> where T : class
    {
        private readonly Table<T> _table;

        public Repository(DataContext dataContext)
        {
            _table = dataContext.GetTable<T>();
        }
   }

public Class TodoService :ITodoService
{
       IRepository<Todo> _todoRepository;
       public TodoService(DataContext dataContext)
       {
           _todoRepository = new Repository<Todo>(dataContext)
       }
       ...
}

}

// Presenter for the user interface

public class TodoPresenter
{
    public void Save()
    {
       Using (DataContext dataContext = DataContextFactory.GetNewContextForDatabase1())
       {
           ITodoService service = new TodoService(dataContext);
            ...
           service.Save(..);
           dataContext.SubmitChanges();           
       }
    }

}

TodoService ITodoService, , , , Windows ( ), .

,

Answer 1

 > I cannot inject data context

, , factory,

public class TodoPresenter
{
    private Func<DataContext> dataContextFactory;
    private Func<DataContext, ITodoService> serviceFactory;

    // created with new TodoPresenter(DataContextFactory.GetNewContextForDatabase1(), 
    //                   dc => new TodoService(dc, 
    //                              new ToDoRepository(dc => new ToDoRepository(dc))));
    public TodoPresenter(Func<DataContext> dataContextFactory, 
                         Func<DataContext, ITodoService> serviceFactory)
    {
        this.dataContextFactory = dataContextFactory;
        this.serviceFactory = serviceFactory;
    }

    public void Save()
    {
        using (DataContext dataContext = this.dataContextFactory())
        {
            ITodoService service = serviceFactory(dataContext);
            // ...
            //service.Save(..);
            //dataContext.SubmitChanges();           
        }

    }
}

, factory

public TodoService(DataContext dataContext, 
         Func<DataContext, IRepository<Todo> todoRepository){...}

  var toDoRepository = new Mock<..>(..);
  var datacontext= new Mock<..>(..);
  var presenter = new TodoPresenter(dc => datacontext, 
                  dc => new TodoService(dc, dc2 => toDoRepository ));

  var TodoService= new Mock<..>(..);
  var datacontext= new Mock<..>(..);
  var presenter = new TodoPresenter(dc => datacontext, 
                  dc => TodoService);

Answer 2

datacontext UnitOfWork. /.

Answer 3

Have you tried creating a datacontext in todoservice?

public interface IRepository<T> where T : class
{
    IEnumerable<T> Find(Expression<Func<T, bool>> where);
    T Single(Expression<Func<T, bool>> where);
    void Save(T item);
    void SubmitChanges();
}

public class Repository<T> : IRepository<T> where T : class
{
    public void Save(T item)
    {
    }

    public void SubmitChanges()
    {
    }
}

// TodoService will have its own local datacontext

public class TodoService :IDisposable
{
   DataContext dataContext;
   IRepository<Todo> _todoRepository;
   public TodoService()
   {
       dataContext = DataContextFactory.GetNewContextForDatabase1();
       _todoRepository = new Repository<Todo>(dataContext);
   }

   public void Dispose()
   {
       dataContext.Dispose();
   }

   void Save(Todo item)
   {
       _todoRepository.Save(item);
   }

   void SubmitChanges()
   {
       _todoRepository.SubmitChanges();
   }
}

// presenter

class TodoPresenter
{
    public void Save()
    {
       using (TodoService service = new TodoService())
       {
           Todo item = null;
           // ...
           service.Save(item);
           service.SubmitChanges();           
       }
    }
}