public override void FeatureActivated(SPFeatureReceiverProperties properties)
{
  // Scope="Web"
  SPWeb web = properties.Feature.Parent as SPWeb;
 
  // Scope="Site"
  SPSite site = properties.Feature.Parent as SPSite;
 
  // Scope="WebApplication"
  SPWebApplication app = properties.Feature.Parent as SPWebApplication;
 
  // Scope="Farm". Does not work
  SPFarm farm = properties.Feature.Parent as SPFarm;
}

Farm != SPFarm

So the last line in the example code does not work. The variables farm is always null.

Here comes the great “SharePoint-naming-convention“… The class to get a farm-context is named SPWebService!

public override void FeatureActivated(SPFeatureReceiverProperties properties)
{
  // Scope="Farm". Works!
  SPWebService farm = properties.Feature.Parent as SPWebService;
}

To make updates and improvements easy I created a custom masterpage which is provisioned via a Feature. A custom feature receiver takes care of setting the masterpage and a feature staple takes care of newly created webs.

Strange things

This works well … Well mostly. In some existing webs my custom masterpage is simply not attached.

Solution

If you set the SPWeb.MasterUrl do not forget to set the SPWeb.CustomMasterUrl, too!

// web = SPWeb
web.MasterUrl = "myPath/to/my.master";
web.CustomMasterUrl = "myPath/to/my.master";

Now my masterpage is attached and used as desired.