Question

I’m trying to use MVP and I notice that my View must know Model that should not happen in MVP I presume.

here is example:

public partial class TestForm : Form, ITestView
{
    public void LoadList(IEnumerable<AppSignature> data)
    {
        testPresenterBindingSource.DataSource = data;
    }
}

public interface ITestView
{
    event EventHandler<EventArgs> Load;
    void LoadList(IEnumerable<AppSignature> data);
}

public class TestPresenter
{
   private ITestView view;

   public TestPresenter(ITestView view)
   {  
       this.view = view;
       view.Load += View_Load;
   } 

   private void View_Load(object sender, EventArgs e)
   {
       var data = // get from model
       view.LoadList(data);
   }
}

and the problem is that in TestForm I need reference to AppSignature.
In all tutorials I saw, there are some simple examples like
public void LoadList(IEnumerable<String> data) where there is no need reference to model. But how i.e DataGridView can publish current row data?

Answer 1

Your form is a View, it is not a Presenter. Thus it should implement interface ITestView:

public interface ITestView
{
    event EventHandler Load;
    void LoadList(IEnumerable<AppSignatureDto> data);
}

And your Presenter is someone, who subscribes to view’s events and uses view properties to read and update view:

public class TestPresenter
{
   private ITestView view;

   public TestPresenter(ITestView view)
   {  
       this.view = view;
       view.Load += View_Load;
   } 

   private void View_Load(object sender, EventArgs e)
   {
       List<AppSignature> signatures = // get from model
       List<AppSignatureDto> signatureDtos = // map domain class to dto
       view.LoadList(signatureDtos);
   }
}

And you form, as I already said, is a view, it does not know anything about presenter and model:

public partial class TestForm : Form, ITestView
{
    public event EventHandler Load;    

    private void ButtonLoad_Click(object sender, EventArgs e)
    {
        if (Load != null)
            Load(this, EventArgs.Empty);
    }

    public void LoadList(IEnumerable<AppSignatureDto> data)
    {
        // populate grid view here
    }
} 

How to deal with reference to domain classes? Usually I provide to view only simple data (strings, integers, dates, etc), or I create data transfer objects, which are passed to view (you can name them FooView, FooDto, etc). You can easily map them with something like AtoMapper:

List<AppSignatureDto> signatureDtos = 
      Mapper.Map<List<AppSignature>, List<AppSignatureDto>>(signatures);