Add base template using sitecore powershell extension

Use Case

It might happen you may have to add base template to all your user defined template. Below is the script to help doing this. I used Adam's code as reference to get this working. During development we could have reach to a stage where we end up with lot of user defined templates and at some point we review and refactor template to have uniform approach. One of the script below can come handy to save some of our refactoring time.

$targetTemplate    = Get-item 'master:/sitecore/templates/User Defined/Common/Data';
$templateFilter    = Get-Item "master:/sitecore/templates/System/Templates/Template";
$templateToBeAddAsBaseTemplate     = Get-Item 'master:/sitecore/templates/User Defined/Common/Data/Carousel'


Get-ChildItem $targetTemplate.FullPath -recurse | Where-Object { $_.TemplateName -eq $templateFilter.Name -and $_.Name -eq "promo"} | ForEach-Object {
    if(-not ($_."__Base template" -match "$($templateToBeAddAsBaseTemplate.Id)")){
           #If not exist then add
         $_."__Base template" = "$( $_."__Base template")|$($templateToBeAddAsBaseTemplate.Id)" 
    }
}

Reference

http://stackoverflow.com/questions/18990973/append-base-template-to-template-using-sitecore-powershell