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DropDown and MultiselectDropDown Controls for ASP.NET

, 6 May 2009 CPOL
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Custom DropDown and MultiselectDropDown controls with data binding support
dropdown-screen-0.PNG

Description

This article discusses about two user controls written in ASP.NET. Working on a project recently, I needed to develop a custom DropDown control with multiselect options in the form of CheckBox. I searched around for something simple, yet useful for my needs, and I wasn't able to find anything, so I developed my own control. Later, I reused the code to create a regular DropDown control (no multiselect checkbox options). The two controls can be merged into one, but I might do that at a later stage. On to the controls. 

DropDown

This control can be bound to a IListSource to fetch data to be populated, in addition to the regular Items collection that can be populated from the asp. Here are a few examples of how this control can be used in ASPX.

<%@ Register Src="Controls/DropDown.ascx" TagName="DropDown" TagPrefix="thp" %>

<thp:DropDown ID="DropDown1" runat="server" Width="200">
     <Items>
          <asp:ListItem Text="Some text" Value="0" Selected="True" />
          <asp:ListItem Text="Another option" Value="1" />
     </Items>
</thp:DropDown>
<thp:DropDown ID="DropDown2" runat="server" Width="200" DataSourceID="DataSource1"
            DataTextField="Name" DataValueField="Id" />
<thp:DropDown ID="DropDown3" runat="server" Width="200" 
	OnNeedDataSource="DropDown3_NeedDataSource"
         DataTextField="Name" DataValueField="Id" OnClientChange="onDropDownChange" />

Here's a screenshot of what the above code would render:

dropdown-screen-1.PNG

Both controls support the following data events:

  • ItemDataBound - Fired after the object has been bound to an Item. The argument passes both the bound object (DataObject) and the ListItem.
  • NeedDataSource - Fired when there's no DataSourceID specified. This event is helpful when you want to manually populate the controls with your data. See the source code provided for specifics on this, you can use either Items collection or create custom list source (or both).

MultiselectDropDown

The code and usage is exactly as the DropDown control. Here's a screenshot of all of the above scenarios:

multidropdown-screen-1.PNG

The styling in the attached project uses .skin files in the default theme. You can easily modify these to fit your needs. Everything can be styled.

I hope you find this code useful. I recommend this to anyone that wants to start developing custom controls as it has very important features implemented, such as the IPostBackDataHandler interface to pass data between postbacks in a custom manner. It also features some nice DataBinding examples and how you can use and modify these to perform specific tasks.

History

  • 6th May, 2009: Initial post

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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About the Author

Tomislav Markovski
Web Developer
Macedonia, The Republic Of Macedonia, The Republic Of
No Biography provided

Comments and Discussions

 
SuggestionThis control doesn't work if there is an async postback in Web page PinmemberPham Dinh Truong10-Jul-13 18:08 
SuggestionJavaScript functions will be duplicated if initiating more than 2 MultiSelectDropDown controls [modified] PinmemberPham Dinh Truong10-Jul-13 8:00 
GeneralMy vote of 5 PinmemberPham Dinh Truong10-Jul-13 0:39 
BugChrome Bug Pinmemberdinesh_22-Mar-13 18:02 
AnswerRe: Chrome Bug [modified] PinmemberPham Dinh Truong10-Jul-13 7:46 
BugTalk about Validation Pinmemberdinesh_5-Jan-13 18:39 
Generalsearchable option for this Pinmemberraj chitty19-Jul-12 0:49 
GeneralMy vote of 5 PinmemberBALAKUMARAN198715-Jun-12 4:26 
QuestionCreate Control Dynamically PinmemberFrank A M20-Apr-12 8:15 
AnswerRe: Create Control Dynamically PinmemberFrank A M1-May-12 10:42 

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