SharePoint Delegate Control with example

General delegates are also called as ambassadors, diplomats, representatives etc.
SharePoint has a couple of delegate controls like

1. AdditionalPageHead
2. GlobalSiteLink0
3. GlobalSiteLink1
4. GlobalSiteLink2
5. PublishingConsole
6. QuickLaunchDataSource
7. SmallSearchInputBox
8. TopNavigationDataSource

Apart from the above controls, we can also create our own custom delegate controls
The XML schema for delegate control is below:

<?xml version="1.0" encoding="utf-8" ?> <Elements xmlns="http://schemas.microsoft.com/sharepoint/">  <Control Id="SmallSearchInputBox" Sequence="100" Url="/templates/mysearchcontrol.ascx"/> </Elements>

In above, properties for the delegate control as Control Id, Sequence and URL. We identify the delegate controls based on Control Id, Sequence number. The Sequence number defines the rank of the delegate, URL describes the source location of the control.
delegate control who’s Sequence id is less has most significant role in SharePoint site and will render on the site as first preference.
 What is the use of delegate control?
Using the delegate control a developer can customize the SharePoint site controls without editing or even touching the master page.
Note: We are not customizing the existing (default) delegate control but we are creating our own control loading onto the SharePoint site.

Let’s suppose assume one scenario, if we want to customize the SharePoint search box (by default SharePoint 2010 site has got input search box with one textbox and one button beside) see figure 1

Figure 1 – SharePoint 2010 Default Search Box

Now I will try to customize the default search box, the requirement is to display the search box with scope drop down list, and also customizing the search button image with a arrow image button.
First open Visual Studio 2010 and click New > Project see figure 2

Figure 2 – Creating New Visual Studio 2010 Project

After project got created, I have deleted the not in use file (you can keep it there won’t be any problem if you don’t delete) because of maintaing clean solution I have removed user control, webpart related files see figure 3

Figure 3 – Solution Explorer File Structure

Then add the following code in Elements.xml file

<?xml version="1.0" encoding="utf-8"?> <Elements xmlns="http://schemas.microsoft.com/sharepoint/" >   <!--<Module Name="VisualWebPart1" List="113" Url="_catalogs/wp">     <File Path="VisualWebPart1\VisualWebPart1.webpart" Url="CustomDelegateControl_VisualWebPart1.webpart" Type="GhostableInLibrary" >       <Property Name="Group" Value="Custom" />     </File>   </Module>-->   <Control      Id="SmallSearchInputBox"      Sequence="23"      ControlClass="Microsoft.SharePoint.Portal.WebControls.SearchBoxEx"      ControlAssembly="Microsoft.Office.Server.Search, Version=14.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c">     <Property Name="QueryPromptString">This control is customized.....</Property>     <Property Name="SearchBoxTableClass">search-box</Property>     <Property Name="GoImageUrl">/_layouts/images/goviewfiles.png</Property>     <Property Name="GoImageUrlRTL">/_layouts/images/goviewfiles.png</Property>     <Property Name="GoImageActiveUrl">/_layouts/images/goviewfiles.png</Property>     <Property Name="GoImageActiveUrlRTL">/_layouts/images/goviewfiles.png</Property>     <Property Name="UseSiteDefaults">true</Property>     <Property Name="FrameType">None</Property>   </Control> </Elements>

In the Element.xml file I have commented the Module section see figure 4

Figure 4 – Custom Delegate Control Element.xml file

Now we are almost done, try to build, deploy and activate the feature which will result in change of SharePoint default search box with your customized control on fly without modifying the master page see figure 5

Figure 5 – SharePoint 2010 Custom Search Input Box