Updating a List Instance

Question

I have a List Instance in Visual Studio. However, every time I deploy the solution, Visual Studio says there is already a list instance with the same URL on the site collection and it needs to delete it first before deploying the new one.

I would like to know if there is a way to upgrade the list instance so that the only things changed when I deploy the list instance will be whatever is new or different compared to the current state of the list instance on the site collection. I would like to maintain all the items in the list as well as the columns and other properties unless they are explicitly changed in Visual Studio.

Answer 1

You should use the new Feature upgrade functionality available in SP2010. You can edit the feature by selecting the Manifest Tab and clicking on Edit Options at the bottom of the screen. Then you can add an UpgradeActions node like this:

<Feature xmlns="http://schemas.microsoft.com/sharepoint/" Version="1.0.0.0">
  <UpgradeActions>
    <VersionRange BeginVersion="0.0.0.0" EndVersion="1.0.0.0">
      <ApplyElementManifests>
        <ElementManifest Location="AdditionalFields\Elements.xml" />
      </ApplyElementManifests>
    </VersionRange>
  </UpgradeActions>
</Feature>

You need to give your feature a version number and use that for the EndVersion. In the Elements.xml only include the new fields that you want to add.

After building your project, use Powershell (Update-SPSolution) to upgrade your solution. Unfortunately, you need to execute code to do the actual upgrade on your feature.

But, this tool should help you with that part: http://spfeatureupgrade.codeplex.com/