Monday, October 15, 2012

How to create a SharePoint Delegate Control that injects JavaScript to all SharePoint pages

Recently, I needed a way to insert some JavaScript files into all pages in all of the SharePoint site collections and sites under an entire web application.

The thought of changing all the master pages in every site collection seemed not only tedious, but unmanageable. Every time a new site collection is created, we would have to remember to modify the master pages. Also, if a site collection owner decided to use their own master pages, we would have no way of maintaining those either.

So, after banging my head trying to come up with a better solution, I stumbled upon the delegate control!

A detailed description of how it works and what it does can be found here:

The beauty of the delegate control is that you can basically overwrite anything in the master page.

I wanted to add a simple JavaScript file to all of the pages in the master page.

So I started by following the example below. I modified this code in step 12 from the hardcoded script to instead read from a JavaScript file that is located in my layouts folder.

  protected override void CreateChildControls()

            string srcScript = "/_layouts/Company/CompanyScript.js";
            this.Controls.Add(new ScriptLink() { Name = srcScript, Language = "javascript", Localizable = false });

The step by step process can also be found here as well:

Step by step process to creating a delegate control:
1.      Start SharePoint development tools in Microsoft Visual Studio 2010.
2.      On the File menu, point to New, and then click Project.
3.      In Project Types, under Visual Basic or C#, select Empty SharePoint Project.
4.      Type EcmaScriptDelegate as the project name. Click OK.
5.      In the SharePoint Customization Wizard, choose Deploy as a farm solution. Click Finish.
6.      In the Solution Explorer, right-click the EcmaScriptDelegate project. Select Add and then New Item.
7.      In the Add New Item dialog box, click the Code group and choose the Class template. Type EcmaScriptDelegateControl as the Name and then click Add.
8.      Next, you must add a reference to System.Web. In the Solution Explorer, right-click the References folder and select Add Reference. In the Add Reference dialog, click the .NET tab and find System.Web in the list. Click OK.
9.      In the EcmaScriptDelegateControl file that is displayed, add the following using statement.
using System.Web.UI.WebControls;
10.  Change the base class of EcmaScriptDelegateControl to WebControl by modifying the following line.
class EcmaScriptDelegateControl : WebControl

11.  Override the OnLoad method by adding the following code.

protected override void OnLoad(EventArgs e)

12.  Inside the OnLoad method, add the following code to put JavaScript on the page.

string helloAlert = "alert('Hello, world!');";
this.Page.ClientScript.RegisterClientScriptBlock(this.GetType(), "popup", helloAlert, true);

Now, you have built the delegate control for the project. Next, you will create the Feature to deploy the control.
To create a Feature to deploy the control
1.      In the Solution Explorer, right-click the EcmaScriptDelegate project and select Add and then New Item.
2.      In the Add New Item dialog box, choose the Empty Element template and type EcmaScriptDelegateFeature as the Name. Click Add.
3.      Insert the following XML inside the Elements element. The Id attribute identifies the delegate where the control is rendered. The ControlAssembly and ControlClass attributes are unique to your control. For more information about how to find the full assembly name, see How to: Create a Tool to Get the Full Name of an Assembly.

The most flexible thing about the delegate control is that it can be defined at the 4 scopes:

·         Web
·         Site collection
·         Web application
·         Farm

Thus, I can set the feature of this scope to activate at any level, and have it immediately show up in ALL of my pages.

The best part is, when you deactivate the feature, it is completely gone and has no impact! No messing with the master page!

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