"Delegate?"
The answer is "Its a Pointer to Function / Method", Delegate Control is a pointer to a Control which can be replaced at runtime based on Feature Activation or Deactivation.Contains a certain predefined element of the SharePoint Products and Technologies environment to replace with another control through a SharePoint Feature.
Real World Example
A user wants to replace the built-in search control with a richer version. He creates a Feature that includes a delegate control to override the delegate control placeholder.
SharePoint Delegate control is a mechanism that we can inject a code or control to the SharePoint Master page with out touching any any code in the SharePoint Master page.
Essentially the Delegate Control provides an alternative to adding user controls and server controls to a .aspx page in the normal way. By this, I mean adding the control to the page by dragging from the toolbox in the development environment or by adding the appropriate markup manually. Instead, with a Delegate Control all we do is add the markup to instantiate a Delegate Control instance, and use a Feature to specify separately which control should actually be loaded. What this effectively gives us is the ability to control what controls are used on a page without having to directly modify and redeploy master pages/page layouts. This extra level of abstraction can be quite powerful, since any feature scope can be used with the Delegate Control.
Here's how it's used:
The Delegate Controls comes into picture when want to brand a SharePoint Site. The delegate control acts like a container control which encapsulates default content (set of child controls inside it). The default content (set of child controls associated with delegate) can be substituted by a specific control, by creating a feature. The ability to override or substitute the delegate controls brings the power & flexibility to brand SharePoint Sites.
The out-of-box SharePoint Foundation Master Page defines many controls like Top Navigation Data Source, Left Navigation Data Source, Search Box and Additional Page Head etc as delegate controls. The list is illustrated below :-
The above listed delegate controls can be substituted at runtime to achieve custom branding. Let’s try to replace the Small Search Input box and see how the delegate control helps for this process. The whole idea is to define a feature for the Custom User Control with same control id mentioned in delegate and the lowest possible sequence number.
Here are the steps below :-
File ---> New Project ---> Empty SharePoint Project
Right Click Project –> Add New item –> User Control . Name it as ‘ReplaceSearchBox’
It automatically creates control templates folder and places the user control underneath that. Create any arbitrary control inside the user control. For the illustration purpose, I’ll add a Calendar Control inside the user control, to visually show a difference how the page looks after the delegate substitution.
Right Click Features –> Add Feature
Set the Feature Scope at Site (site-collection level)
Right Click Solution ---> Add New Item –> Empty Element
We’d be leveraging Elements.xml file for the delegate substitution process. Before jumping on to the substitution lets understand how the out-of-box Search Box is defined using Feature.
Build the Project, Package it and Deploy.
Now you can see the the custom user control with Calendar replaces the Delegate control.
SharePoint Delegate control is a mechanism that we can inject a code or control to the SharePoint Master page with out touching any any code in the SharePoint Master page.
“ is a container type control which can holds child controls on it “
Essentially the Delegate Control provides an alternative to adding user controls and server controls to a .aspx page in the normal way. By this, I mean adding the control to the page by dragging from the toolbox in the development environment or by adding the appropriate markup manually. Instead, with a Delegate Control all we do is add the markup to instantiate a Delegate Control instance, and use a Feature to specify separately which control should actually be loaded. What this effectively gives us is the ability to control what controls are used on a page without having to directly modify and redeploy master pages/page layouts. This extra level of abstraction can be quite powerful, since any feature scope can be used with the Delegate Control.
Here's how it's used:
The Delegate Controls comes into picture when want to brand a SharePoint Site. The delegate control acts like a container control which encapsulates default content (set of child controls inside it). The default content (set of child controls associated with delegate) can be substituted by a specific control, by creating a feature. The ability to override or substitute the delegate controls brings the power & flexibility to brand SharePoint Sites.
The out-of-box SharePoint Foundation Master Page defines many controls like Top Navigation Data Source, Left Navigation Data Source, Search Box and Additional Page Head etc as delegate controls. The list is illustrated below :-
<SharePoint:DelegateControl runat="server" ControlId="AdditionalPageHead"
AllowMultipleControls="true"/>
<SharePoint:DelegateControl runat="server" ControlId="GlobalNavigation" />
<SharePoint:DelegateControl runat="server" ID="GlobalDelegate0" ControlId="GlobalSiteLink0" />
<SharePoint:DelegateControl ControlId="GlobalSiteLink2" ID="GlobalDelegate2" Scope="Farm"
runat="server" />
<SharePoint:DelegateControl runat="server" ControlId="PublishingConsole"
Id="PublishingConsoleDelegate">
</SharePoint:DelegateControl><SharePoint:DelegateControl ControlId="GlobalSiteLink3" Scope="Farm"
runat="server" />
<SharePoint:DelegateControl runat="server" ControlId="SmallSearchInputBox" Version="4" />
<SharePoint:DelegateControl runat="server" ControlId="TopNavigationDataSource"
Id="topNavigationDelegate"/>
The above listed delegate controls can be substituted at runtime to achieve custom branding. Let’s try to replace the Small Search Input box and see how the delegate control helps for this process. The whole idea is to define a feature for the Custom User Control with same control id mentioned in delegate and the lowest possible sequence number.
Here are the steps below :-
File ---> New Project ---> Empty SharePoint Project
Right Click Project –> Add New item –> User Control . Name it as ‘ReplaceSearchBox’
It automatically creates control templates folder and places the user control underneath that. Create any arbitrary control inside the user control. For the illustration purpose, I’ll add a Calendar Control inside the user control, to visually show a difference how the page looks after the delegate substitution.
<asp:Calendar ID="Calendar1" runat="server"></asp:Calendar>
It automatically creates control templates folder and places the user control underneath that.
Right Click Features –> Add Feature
Set the Feature Scope at Site (site-collection level)
Right Click Solution ---> Add New Item –> Empty Element
We’d be leveraging Elements.xml file for the delegate substitution process. Before jumping on to the substitution lets understand how the out-of-box Search Box is defined using Feature.
The Search Box is defined in both the Features ‘OSearchBasicFeature’ and ‘OSearchEnhancedFeature’ in the location
C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\14\TEMPLATE\FEATURES
The definition looks like the following :-
<Elements xmlns="http://schemas.microsoft.com/sharepoint/"> <Control Id="SmallSearchInputBox" Sequence="50" ControlClass="Microsoft.SharePoint.Portal.WebControls.SearchBoxEx"
ControlAssembly="Microsoft.Office.Server.Search, Version=14.0.0.0, Culture=neutral,
PublicKeyToken=71e9bce111e9429c">
<Property Name="GoImageUrl">/_layouts/images/gosearch15.png</Property>
<Property Name="GoImageUrlRTL">/_layouts/images/gosearchrtl15.png</Property>
<Property Name="GoImageActiveUrl">/_layouts/images/gosearchhover15.png</Property>
<Property Name="GoImageActiveUrlRTL">/_layouts/images/gosearchrtlhover15.png</Property>
<Property Name="DropDownMode">ShowDD</Property>
<Property Name="SearchResultPageURL">/_layouts/osssearchresults.aspx</Property>
<Property Name="ScopeDisplayGroupName"></Property>
<Property Name="FrameType">None</Property>
</Control>
</Elements>
<Elements xmlns="http://schemas.microsoft.com/sharepoint/">
Here the Id & Sequence number of the control plays an important role.
To substitute this out-of-box SmallSearchInput box, Let’s define Elements.xml file for Feature. The id of the control should match with id of control to be replaced.
The Sequence number should be less than the sequence number of the out-of-box control. In this case we’re assigning sequence number as 10, so that the control with the lowest
sequence number gets precedence.
<Control Id="SmallSearchInputBox" Sequence="10" ControlSrc ="~/_controltemplates/ReplaceSearchBox/ReplaceSearchBox.ascx"> </Control></Elements>
Since we’re using an user control for substitution, we need to make sure that ControlSrc attribute is defined. There is no need to define ControlClass and ControlAssembly attribute here.
I did define all the 3 attributes, but the substitution was not happening. I’ve learnt that it’s enough to define the ControlSrc attribute itself. Do not define all 3 attributes for user control,
the substitution will not happen. If you are using Custom Control, it makes sense to use ControlClass and ControlAssembly attribute.
The final Solution Package looks like the following :-
Build the Project, Package it and Deploy.
Now you can see the the custom user control with Calendar replaces the Delegate control.
No comments:
Post a Comment