Question

I have a class MyListView, it inherits from ASP.NET ListView. I would like to implement a default behaviour – if a programmer doesn’t specify EmptyDataTemplate in aspx code, the MyListView will use a predefined default template (class MyEmptyDataTemplate).

What I have tried is this:

public class MyListView : ListView
{
    protected override void CreateChildControls()
    {
        if (EmptyDataTemplate == null)
            EmptyItemTemplate = new MyEmptyDataTemplate();

        base.CreateChildControls();                         
    }
}

The MyEmptyDataTemplate implements ITemplate interface. The problem is, that InstantiateIn() method of the MyEmptyDataTemplate is never called, and my default template never appears in case there are no records in datasource. Apparently I wrong understand the ListView component lifecycle and template should be set somewhere else.

Answer 1

Try to do this on the Init event:

public class MyListView : ListView
{
    public MyListView()
    {
       this.Init += (o, e) =>
            { 
                if (EmptyDataTemplate == null)
                     EmptyDataTemplate = new MyEmptyDataTemplate();
            };
    }
}

edit
After checking this again I realized that EmptyDataTemplate was checked if emtpy, but the template which has been assigned is EmptyItemTemplate. However both methods are good to instantiate the templates..