Category Archives: User Control

Using Web User Controls

So you’ve written a nice little Web User Control, but how do you use it?

Using your Web User Control is actually really simple. I am not going to address creating one just how to add that reference to your nice little .ascx file. There are two ways to do this, as a page directive or as I prefer, in the web.config file.

<%@ Register Src="MyControl.ascx" TagName="MyControl" TagPrefix="uc1" %>

For myself I prefer to use the web.config setting. In your controls section which is inside the pages section you just add them. In my example below I wanted to show one that goes to a dll (the Ajax Control Toolkit) and one that goes to an ascx file inside a UserControl folder in my project.

<pages viewStateEncryptionMode="Always">
    <add tagPrefix="cc1" namespace="AjaxControlToolkit" assembly="AjaxControlToolkit"/>
    <add tagPrefix="my" tagName="FormFields" src="~/CustomControls/MyFormFields.ascx"/>

You will reference your control with <tagPrefix:tagName>.  The tagPrefix is the first half of the control tag and should be fairly obvious and is something you control.  So instead of <asp:  you would have <my: or <cc1:  For the other half of the tag it is a bit different, the ascx sets the tag name, <my:FormFields  …. />  In the namespace one it will be one of the objects in the dll, <cc1:Accordian … />.

Please see the MSDN site for Walkthrough: Creating Reusable Elements with ASP.NET User Controls.

Web User Control Events

Ever want to have an event for a Web User Control that the parent page can consume?  Well you can, and it is fairly simple.

I am not an expert since I just figured this out myself so here we go.

There are three basic things you need to do for each event.

  1. Create a public delegate variable in your User Control
  2. Create a public event event for the type of delegate
  3. Create a protected virtual method

So lets see some code.

//Public variables and methods
public delegate void ItemClickEvent(object sender, EventArgs e);
public event ItemClickEvent ItemClick;

//Protected Methods
protected virtual void OnItemClicked(object sender, EventArgs e)
    if (ItemClick != null)
        ItemClick(this, e);

The property in the page with this user control will be called OnItemClick.  Notice I do not have anything named OnItemClick.  The only public names are ItemClickEvent, which is a delegate and the event itself, ItemClick.  So I assume that .NET adds the On to the front of your event name.