Replacing delegate controls with custom actions

When using jQuery in a SharePoint application, you obviously need to deploy the jQuery javascript file. The deploy part is no big deal, the referencing is a bit more complex. In this post is the detail of a new way to reference the resources, it involves using Custom Action to load external resources such as javascript or css.

Current Solution

As explained by Jan Tielens (http://weblogs.asp.net/jan/archive/2008/11/20/sharepoint-2007-and-jquery-1.aspx there are usually three solutions considered to be available to do that:

Add a <script src> tag in a Content Editor Web Part
Add a <script src> tag in the Master Page itself
Add a <script src> tag dynamically in the <head> using a DelegateControl placed in the standard master pages

In my case, only the third solution was usable. So I went with it, created my feature, added it to my solution.

The problem

The story would have ended here if it wasn’t for a detail I discovered quickly enough; the standard publishing pages (BlueGlassBand and so forth) do not have the AdditionalPageHead delegate control defined. Thus my solution worked really well with collaboration pages but failed on publishing pages.

The obvious solution was to modify the master page used by my client to add the Delegate Control tag but the client didn’t want any modification to the master page. Thus I was at this point :

How do I add a reference to some javascript and css files in the HTML <head> section of a page generated by a master page that doesn’t include any DelegateControl and that I can’t modify.

The solution

After digging a bit I found a very surprising (to me at least) but fully working solution. Use a Custom Action.

Before you start thinking I am nuts, let me explain, If you take a close look at the MSDN you will see that you can specify a ControlAssembly and a ControlClass, guess what, the class specified will do the actual rendering. Custom Actions aren’t just for Site Action Menu entries, ECB and so forth.

So here is more detail:

Create a class inheriting from CompositeControl
Override the constructor so that I can plug a method in the Load event.
In my method triggered on load, access the page header and add a LiteralControl to declare the scripts and css I need

And here is a stripped down but fully working version of my code :

using System;
using System.Collections.Generic;
using System.Text;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
using System.Web.UI;

namespace ItemsInTheSafeControl
{
  class SiteActionMenu : CompositeControl
  {
      public const string mStrIncludedRessources = "<script type=\"text/javascript\" src=\"/_layouts/jquery-1.3.2.min.js\">";

      public SiteActionMenu()
      {
          this.Load += new EventHandler(SiteActionMenu_Load);
      }
      protected void SiteActionMenu_Load(object Sender, EventArgs E)
      {
          LiteralControl vLiteralControl = new LiteralControl(SiteActionMenu.mStrIncludedRessources);
          this.Page.Header.Controls.Add(vLiteralControl);

      }
      protected override void Render(HtmlTextWriter Writer)
      {
      }
  }
}

To plug this code as a custom action, I use the following ElementManifest

<?xml version="1.0" encoding="utf-8" ?>
<Elements xmlns="http://schemas.microsoft.com/sharepoint/">
<CustomAction
      Id="SAG_CR_Ressources_Deploy_Action"
      Location="Microsoft.SharePoint.StandardMenu"
      GroupId="SiteActions"
      ControlAssembly="SAG.CommentsRating, Version=1.0.0.0, Culture=neutral, PublicKeyToken=406cabeaa3d2932a"
      ControlClass="SAG.CommentsRating.WebParts.SiteActionMenu">
</CustomAction>
</Elements>

Now you just package the ElementManifest in a feature, add your dll and create a solution out of it (wspbuilder is my tool of choice). Your solution manifest will need to specify a SafeControl tag to be added for your class/namespace in the web.config for your CompositeControl.

Here you go, a non-intrusive quite generic solution to plug additional resources into SharePoint.

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Saturday, March 06, 2010