Question

I’ve just started using the MVP pattern in the large ASP.NET application that I’m building (re-building actually) and I am having a hard time figuring out how I should be using Events applied to the view.

Say I have 2 drop down lists in a User Control, where one is dependent on the other’s value:

<%@ Control Language='vb' AutoEventWireup='false' CodeBehind='ucTestMVP.ascx.vb' Inherits='.ucTestMVP' %>     <asp:DropDownList ID='ddlCountry' runat='server' AutoPostBack='True' /> <asp:DropDownList ID='ddlCity' runat='server' /> 

How should the AutoPostBack Event be defined in the interface? Should it be an event that is handled by the User Control like this:

Public Partial Class ucTestMVP   Inherits System.Web.UI.UserControl   Implements ITestMVPView    Protected Sub PageLoad(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load     If Not Page.IsPostBack Then       Dim presenter As New TestMVPPresenter(Me)       presenter.InitView()     End If   End Sub    Private Sub ddlCountrySelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles ddlCountry.SelectedIndexChanged     Dim presenter as New TestMVPPresenter(Me)     presenter.CountryDDLIndexChanged()   End Sub  End Class 

Or should there be an event defined at the Interface? If this is the preferred pattern, how do I add events to be handled and used?

Answer 1

I don’t know if there’s a universally preferred pattern. I tend to prefer adding the event to the view interface and having the presenter respond to the view. I described this pattern in more detail here.