FFTF - Automatic removal of lists when deactivating ListInstance feature

Creating lists using ListInstances is quite easy to do within a feature. However, deleting those lists again when deactivating that feature does not happen automatically (which is understandable, since you don't want to lose all data in the list when accidentally deactivating the feature ...).

So, I created a feature receiver to do the job for you :) The receiver simple deletes all lists created by a ListInstance tag in the feature.

This is how I did it:

1. The feature.xml file

<?xml version="1.0" encoding="utf-8" ?>
<Feature xmlns="http://schemas.microsoft.com/sharepoint/"
         DefaultResourceFile="blog"
         Id="{40B0BD50-8A65-4cc3-99E4-28024DA1A487}"
         Title="Blogging list instances"
         Description="This feature enables the custom list instance definitions."
         Version="1.0.0.0"
         Scope="Web"
         ReceiverAssembly="SharePoint.Blogging, Version=1.0.0.0, Culture=neutral, PublicKeyToken=bc158afeef6140c2"
         ReceiverClass="SharePoint.Blogging.ListInstanceRemover">
  <ElementManifests>
    <ElementManifest Location="Elements.xml"/>
  </ElementManifests>
</Feature>

Notice that I set the DefaultResourceFile property to a self-created resource file, which is deployed in the 12/Resources folder.

2. The elements.xml file

<?xml version="1.0" encoding="utf-8" ?>
<Elements xmlns="http://schemas.microsoft.com/sharepoint/">
  <ListInstance Id="0"
                Description="A test list for the blogging article."
                FeatureId="{00BFEA71-DE22-43B2-A848-C05709900100}"
                OnQuickLaunch="TRUE"
                QuickLaunchUrl="/BlogList/AllItems.aspx"
                TemplateType="100"
                Title="$Resources:ListInstances_List_Title"
                Url="BlogList" />
  <ListInstance Id="1"
                Description="A test document library for the blogging article."
                FeatureId="{00BFEA71-E717-4E80-AA17-D0C71B360101}"
                OnQuickLaunch="TRUE"
                QuickLaunchUrl="/BlogDocLib/Forms/AllItems.aspx"
                TemplateType="101"
                Title="$Resources:blog,ListInstances_DocLib_Title;"
                Url="BlogDocLib" />
</Elements>

3. The feature receiver (the important part)

To create a feature receiver, we create a class overriding SPFeatureReceiver.

using System;

using Microsoft.SharePoint;
using Microsoft.SharePoint.Administration;
using Microsoft.SharePoint.Utilities;
using System.Globalization;

namespace SharePoint.Blogging
{
    public class ListInstanceRemover : SPFeatureReceiver
    {
        public override void FeatureDeactivating(SPFeatureReceiverProperties properties)
        {
            CultureInfo ci = System.Globalization.CultureInfo.InvariantCulture;
            SPElementDefinitionCollection elementFiles = properties.Definition.GetElementDefinitions(ci);

            foreach (SPElementDefinition elementFile in elementFiles)
            {
                if (elementFile.ElementType == "ListInstance")
               {
                    string defaultResourceFile = properties.Feature.Definition.DefaultResourceFile;
                    string listTitle = SPUtility.GetLocalizedString(elementFile.XmlDefinition.Attributes["Title"].Value, defaultResourceFile, Convert.ToUInt32(ci.LCID));

                    SPWeb web = properties.Feature.Parent as SPWeb;
                    SPList list = web.Lists[listTitle];

                    list.Delete();
                }
            }
        }

        public override void FeatureActivated(SPFeatureReceiverProperties properties)
        {
        }
        public override void FeatureInstalled(SPFeatureReceiverProperties properties)
        {
        }
        public override void FeatureUninstalling(SPFeatureReceiverProperties properties)
        {
        }
    }
}

You might also notice me using the SPUtility.GetLocalizedString method, which actually is very handy to use when dealing with resource files, as it translates the resource string into the localized value.

There, that's it. I hope it helps someone in some way ... ;)

Posted on SharePoint Blogs