Activating the Document ID feature by code causes document sets welcome pages to show each web part twice

This is a weird one - I have a feature, that when activated loops over a list of other features and activates them - using "Force" :

site.Features.Add(currentFeatureID, true);


This works fine on most sites, but in Document Center sites, where the document ID feature is already activated document sets in the site suddenly show the web parts on the welcome page twice. I debugged it, and it turns out that this happens when the document ID feature is the culprit. However, this doesn't happen if I activate the ID feature using powershell.


My only solution at the moment is to check if the feature is already activated before activating it. This stopped the problem, but doesn't explain it.

Finding if a site column exists in a site, by ID

Scenario - you have an ID of a site column (SPField belonging to SPWeb)and you want to find out if there is a field by that ID in the collection.


Problem: if you try something like:


web.Fields[fieldID] == null



The result is an exception if the field doesnt exist. What a shame.

The solution is to use the Contains method of the Fields collection:


web.Fields.Contains(fieldID)

*Thanks Ofer Gal for pointing this out.