SharePoint: Active/Deactivate Feature programmatically

Sometimes you may need to activate/deactivate features programmatically. In my case, I needed to do some synchronization from a Synchronization feature. As part of the synchronization, I needed to move data from one list to another. However the destination list had event receiver attached. The event receiver was attached using another feature (say ListItemEventReceiverAttacher). So I needed to deactivate the feature (i.e., ListItemEventReceiverAttacher) to make sure that event receiver associated to the list is not active. So let’s come to the point rather than beating around the bush.

First of all, your feature can have scope of web, site or webapplication or Farm. so you need to get the feature first. You can do so by accessing Features properties of Site or web as shown below:

1. Get the activated Features available in the WebApplication/Site/Web level

var webApplicationFeatures = webapplication.Features
var webFeatures = web.Features;
var siteFeatures = site.Features;

2. once you have got the features you can find your feature by feature id or name, if the feature is activated, as shown below:

var feature = site.Features.SingleOrDefault(sf => sf.DefinitionId == myFeatureDefinitionId);

var feature = site.Features.SingleOrDefault(sf => sf.Definition.DisplayName.Equals("Feature Title"));

If the feature is null then the feature is not activated. Only activated features will be available through site.Features/web.Features property.

3. If feature is not activated, you can activate the feature as shown below:

if(feature==null)//if feature is not activated
{
   site.Features.Add(featureId);//activate feature
}

4. If the feature is activated, you can deactivate the feature as shown below:

if(feature!=null)//if feature is activated
{
    site.Features.Remove(feature.DefinitionId);//deactivate feature
}

Important: One important thing to notice that once you activate/deactivate a feature against an object (SPWebApplication/SPSite/SPWeb), you need to open a new SPWebApplication/SPSite/SPWeb object to get the changes you made. The scenario shown below:

using (SPSite site=new SPSite("http://myserver"))
{
    //Activate or deactivate feature
    //the changes will not be available in this scope.
}
using (SPSite site=new SPSite("http://myserver"))
{
    //Changes made to the feature in upper using block will be effeftive here
}