TFS 2013 - Update MSBuild Parameters from pre-build PowerShell script - powershell

Question

I have recently upgraded from TFS 2012 to TFS 2013 and am trying to use the new template (TfvcTemplate.12.xaml). I need to set the version numbers of my .NET applications and WiX installers as part of this process.
In my TFS 2012 process I customised the build template using TFS Community Build Extensions to do the following:
Generate a version number. The Major and Minor version numbers are static, the release number is the number of days since 2014-11-25, the build number is the number of times the build definition has run today.
Update all AssemblyInfo.cs files with the new version number
Update the MsBuildArguments argument to pass the version as a parameter. This is so that I can set the version number in my WiX installers.
Before I resort to customising the build template again I would like to try to achieve the above using a Pre-build PowerShell script.
Items 1 and 2 were easy in PowerShell but I am stuck with the third requirement. Is it possible for the Pre-build PowerShell script to update the MSBuildArguments?

Answer 1

I think there is a simpler way to do this. This is what we did.
Created an include file called Version.wsi. The file contains these 4 lines:
<?xml version="1.0" encoding="utf-8"?>
<Include>
<?define CurrVersion="1.0.0.0" ?>
</Include>
In our wxs file, right after the line
<Wix xmlns:util="http://schemas.microsoft.com/wix/UtilExtension" xmlns="http://schemas.microsoft.com/wix/2006/wi" >
add the following:
<?include Version.wxi ?>
In your wxs file use the variable $(var.CurrVersion) where you currently specify your version.
Now all you need to include in your powershell script is some code to modify the wxi file with the correct version number. This is how I do it:
function UpdateVersion($newVersion)
{
$wxiFile = gci "$Somedir\Version.wxi"
#clear the read-only bit just in case
Set-ItemProperty $wxiFile -name IsReadOnly -value $false -Force
$newContent = $content -replace "1.0.0", $prodVersion
Set-Content -Path $wxiFile -Value $newContent
}