Generate a Windows Installer transform file (MST) using PowerShell

I recently needed to generate a Windows Installer transform file (MST) using PowerShell.  I’ve ripped out some excerpts below to demonstrate inserting rows, querying tables, retrieving properties and generating a transform.  Using this example for reference, you should be able to accomplish most tasks using Powershell and the Windows Installer object.

Tip: Make sure you enclose all table and column names with a double backtick to avoid ‘OpenView,Sql’ errors during OpenView() calls!  By default a single backtick in Powershell acts as an escape character, so we are required to use two of these.

$msiOpenDatabaseModeReadOnly = 0
$msiOpenDatabaseModeTransact = 1
$msiTransformErrorNone = 0
$msiTransformValidationNone = 0
$msiFolder = "C:\alkaneMSI\"
$database1Path = $msiFolder + "example.msi"
$database2Path = $database1Path + "_bak"
$MSTPath = $msiFolder + "New_MST.mst"
 
#If backup doesn't already exist, make a copy to make our changes to
if (!(Test-Path -Path $database2Path))
{
	Copy-Item -Path $database1Path -Destination $database2Path
}
	
#Remove MST if already exists
If (Test-Path $MSTPath){
		Remove-Item $MSTPath
}

#open original MSI in ReadOnly mode
$windowsInstaller = New-Object -ComObject WindowsInstaller.Installer         	 
$database1 = $windowsInstaller.GetType().InvokeMember(
	"OpenDatabase", 
	"InvokeMethod", 
	$Null, 
	$windowsInstaller, 
	@($database1Path, $msiOpenDatabaseModeReadOnly)
)  

#open 'backup' MSI in transact mode
$database2 = $windowsInstaller.GetType().InvokeMember(
	"OpenDatabase", 
	"InvokeMethod", 
	$Null, 
	$windowsInstaller, 
	@($database2Path, $msiOpenDatabaseModeTransact)
) 
	
#use the TablePersist method to see if the CustomAction table exists
$tableExists =  $database2.GetType().InvokeMember(
	"TablePersistent",
	"GetProperty",
	$Null,
	$database2,
	"CustomAction"
)	

#If CustomAction table does not exist
if ([int]$tableExists -ne 1)
{
	#Create CustomAction table
	$query = "CREATE TABLE ``CustomAction`` ( ``Action`` CHAR(72) NOT NULL, ``Type`` SHORT NOT NULL, ``Source`` CHAR(64), ``Target`` LONGCHAR PRIMARY KEY ``Action``)"
	$View = $database2.GetType().InvokeMember(
		"OpenView",
		"InvokeMethod",
		$Null,
		$database2,
		($query)
	)
	$View.GetType().InvokeMember("Execute", "InvokeMethod", $Null, $View, $Null)		
	$View.GetType().InvokeMember("Close", "InvokeMethod", $Null, $View, $Null)
	[System.Runtime.Interopservices.Marshal]::ReleaseComObject($View) | Out-Null
}

#Insert a test Custom Action
$query = "INSERT INTO ``CustomAction`` (``Action``,``Type``,``Source``,``Target``) VALUES ('TestCA',38,'','MsgBox ""test""')"

$View = $database2.GetType().InvokeMember(
	"OpenView",
	"InvokeMethod",
	$Null,
	$database2,
	($query)
)
$View.GetType().InvokeMember("Execute", "InvokeMethod", $Null, $View, $Null)		
$View.GetType().InvokeMember("Close", "InvokeMethod", $Null, $View, $Null)
[System.Runtime.Interopservices.Marshal]::ReleaseComObject($View) | Out-Null

#We want to sequence the Custom Action to run after CostFinalize, so we get the sequence number for CostFinalize	
$query = "SELECT ``Sequence`` FROM ``InstallExecuteSequence`` WHERE ``Action`` = 'CostFinalize'"
$View = $database2.GetType().InvokeMember(
	"OpenView",
	"InvokeMethod",
	$Null,
	$database2,
	($query)
)
$View.GetType().InvokeMember("Execute", "InvokeMethod", $Null, $View, $Null)

$record = $View.GetType().InvokeMember(
	"Fetch",
	"InvokeMethod",
	$Null,
	$View,
	$Null
)

$IESequence = [int]0
while ($record -ne $null) {
	$IESequence = [int]$record.GetType().InvokeMember("StringData", "GetProperty", $Null, $record, 1)
	
	$record = $View.GetType().InvokeMember(
		"Fetch",
		"InvokeMethod",
		$Null,
		$View,
		$Null
	)
}
[System.Runtime.Interopservices.Marshal]::ReleaseComObject($View) | Out-Null

#We insert the Custom Action into the InstallExecuteSequence table, adding one to the sequence number retrieved from CostFinalize
$query = "INSERT INTO ``InstallExecuteSequence`` (``Action``,``Sequence``) VALUES ('TestCA','" + ($IESequence+1) + "')"
$View = $database2.GetType().InvokeMember(
	"OpenView",
	"InvokeMethod",
	$Null,
	$database2,
	($query)
)
$View.GetType().InvokeMember("Execute", "InvokeMethod", $Null, $View, $Null)		
$View.GetType().InvokeMember("Close", "InvokeMethod", $Null, $View, $Null)
[System.Runtime.Interopservices.Marshal]::ReleaseComObject($View) | Out-Null	

#Commit the changes to our backup database
$database2.GetType().InvokeMember("Commit", "InvokeMethod", $Null, $database2, $Null)
	
#Generate a transform (the difference between our original MSI and our Backup MSI)	
$transformSuccess = $database2.GetType().InvokeMember(
	"GenerateTransform", 
	"InvokeMethod", 
	$Null, 
	$database2, 
	@($database1,$MSTPath)
)  
			
#Create a Summary Information Stream for the MST
$transformSummarySuccess = $database2.GetType().InvokeMember(
	"CreateTransformSummaryInfo", 
	"InvokeMethod", 
	$Null, 
	$database2, 
	@($database1,$MSTPath, $msiTransformErrorNone, $msiTransformValidationNone)
)  

#Release objects from memory
[System.Runtime.Interopservices.Marshal]::ReleaseComObject($database1) | Out-Null 
[System.Runtime.Interopservices.Marshal]::ReleaseComObject($database2) | Out-Null
[System.Runtime.Interopservices.Marshal]::ReleaseComObject($windowsInstaller) | Out-Null

#Delete backup database
If (Test-Path $database2Path){
	Remove-Item $database2Path
}