Question

I’m developing a custom server control in Asp.NET (.NET 3.5) which inherits the CompositeControl class. Inside my control I’m overriding the CreateChildControls() method to generate a mixture of html and Asp.NET server controls. Some of the Asp.NET controls which are added are LinkButtons (which each have their Command event handler set to a method within my control). What I’m finding is that the first time one of these LinkButtons is clicked a postback is triggered and the event handler method is correctly fired. Inside this event handler method CreateChildControls() is explicitly called to regenerate the control in response to the postback. What I then find is that subsequent clicks of the LinkButtons postbacks fail to raise the event handler method.

I assume that the way I’m handling the regeneration of the control on postback must be at fault, but I can’t figure out what to do – I am aware of the fact that on that first postback CreateChildControls() is called twice which probably isn’t ideal but since CreateChildControls is called before any events are raised, I don’t see a way around this.

A simplified version of my control class is shown below:

public class SearchResults : CompositeControl
{
    private int PageIndex = 0;

    protected override void CreateChildControls()
    {
            //do stuff here e.g.
            LinkButton prevLink = new LinkButton();
            prevLink.Text = "< Prev";
            prevLink.CommandArgument = (PageIndex - 1).ToString();
            prevLink.Command += new CommandEventHandler(PagerLinkCommand);
            this.Controls.Add(prevLink);
    }

    protected void PagerLinkCommand(object sender, CommandEventArgs e)
    {
        PageIndex = int.Parse(e.CommandArgument.ToString());
        CreateChildControls();
    }
}

EDIT
The problem here was caused by the fact that the control is used in a Sitecore site and I had forgotten to register the control type in the web.config file with a <typesThatShouldNotBeExpanded> entry. This entry is used to prevent server controls from having their events messed up by Sitecore – this can cause similar problems for standard server controls such as ListView, GridView and Repeater etc. My web.config was modified as shown below:

  <typesThatShouldNotBeExpanded>
    <type>System.Web.UI.WebControls.Repeater</type>
    <type>System.Web.UI.WebControls.DataList</type>
    <type>System.Web.UI.WebControls.GridView</type>
    <type>MyNamespace.MyCustomControl</type> <!-- This is the bit I added -->
  </typesThatShouldNotBeExpanded>

Answer 1

The reason for this behaviour was not down to the server control itself, but was Sitecore-related. In order for Sitecore to not interfere with server control postbacks, it is necessary to add an entry under the typesThatShouldNotBeExpanded section in the web.config file as shown below.

<typesThatShouldNotBeExpanded>
  <type>System.Web.UI.WebControls.Repeater</type>
  <type>System.Web.UI.WebControls.DataList</type>
  <type>System.Web.UI.WebControls.GridView</type>
  <type>MyNamespace.MyCustomControl</type> <!-- This is the bit I added -->
</typesThatShouldNotBeExpanded>