从类库程序集设置ASP.NET页面控件

Question

I use model view presenter approach for ASP.NET web site. The presentation part is compiled in separate class library where view contracts and presenters are defined:

MyPresentation assembly
IMyView
{
     DisplayText(string text);
}
MyPresenter
{
     public IMyView View { get; set; }
     public DisplayText()
     {
         string text = Generate();
         View.DisplayText(text);   
     } 
}

MyWebApplication assembly
public partial class MyForm : System.Web.UI.Page, IMyView
{
    public void DisplayText(string text)
    {
        this.myLabel.Text = text;  
    }
    ...
    protected void myButton_Click(object sender, EventArgs e) 
    {
        Presenter.DisplayText(); // calls this.DisplayText()     
    }        
}

However after stepping out of Presenter.DisplayText() Text property of myLabel becomes null again as though no assignment were done. By all means if you replace the only line in myButton click event with direct setting of myLabel Text property everything stays assigned.

Answer 1

Does the Generate method return a non-null string? That looks like about the only culprit in this case. It might also explain why setting myLabel directly works.

To diagnose, pass a literal string to View.DisplayText instead of calling Generate .