PowerShell function to convert XLS files to XLSX

Migrations… always fun to do when you can automate them.
Let’s say that you migrate from Office 2003 to Office 2010. You may want to convert your ‘old’ XLS files to the new XLSX format.
But you would you do that? I believe there is a tool for that, but my customer asked me to script everything.

So, here’s a script that covers two migration scenario’s:

1) Create the new XLSX files next to the XLS files.
2) Create the new XLSX files in a path that is defined when calling the function.

I also found that hiding the Excel GUI will still convert some files with curruptions in them, when the GUI would provide an error… so I added the -Visible parameter

Have fun migrating!

function ConvertTo-XLSX {
    <#
    .SYNOPSIS
    XLS files within a provided path are recursively enumerated and convert to XLSX files.
    .DESCRIPTION
    XLS files within a provided path are recursively enumerated and convert to XLSX files.
    The original XLS files remain intact, a new XLSX file will be created.
    .PARAMETER Path
    This parameter takes the input of the path where the XLS files are located.
    .PARAMETER Visible
    Using the parameter will show you how Excel does the work. Not using the parameter will enable Excel 
    to accomplish its tasks in the background.

    Note: Bu not using this parameter you will be able to convert some XLS files which have corruptions 
    in them, when using the parameter and therefor the Excel GUI will give you an error.
    .PARAMETER ToFolder
    This parameter enables you to provide a location where the file is saved. When this parameter is 
    not used, the file will be saved as an XLS file in the same location as where the 
    original XLS file is located.
    .EXAMPLE
    ConvertTo-XLSX -Path 'D:\Data\2012'
    .EXAMPLE
    ConvertTo-XLSX -Path 'D:\Data\2012' -Visible
    .EXAMPLE
    ConvertTo-XLSX -Path 'D:\Data\2012' -ToFolder 'D:\Data\2012XLSX'
        .EXAMPLE
    ConvertTo-XLSX -Path 'D:\Data\2012' -Visible -ToFolder 'D:\Data\2012XLSX'
    #>
    [cmdletbinding()]
    param (
        [parameter(mandatory=$true)][string]$Path,
        [parameter(mandatory=$false)][switch]$Visible,
        [parameter(mandatory=$false)][string]$ToFolder
    )
    begin {
        $xlFixedFormat = [Microsoft.Office.Interop.Excel.XlFileFormat]::xlWorkbookDefault
        $Excel = New-Object -ComObject excel.application
        if ($Visible -eq $true) {
            $Excel.visible = $true
        } else {
            $Excel.visible = $false
        }
        $filetype = "*xls"
    } process {
        if (Test-Path -Path $Path) {
            Get-ChildItem -Path $Path -Include '*.xls' -recurse | ForEach-Object {
                if ($ToFolder -ne '') {
                    $FilePath = Join-Path $ToFolder $_.BaseName
                    $FilePath += ".xlsx"
                } else {
                    $FilePath = ($_.fullname).substring(0, ($_.FullName).lastindexOf("."))
                    $FilePath += ".xlsx"
                }
                $WorkBook = $Excel.workbooks.open($_.fullname)
                $WorkBook.saveas($FilePath, $xlFixedFormat)
                $WorkBook.close()
                $OldFolder = $Path.substring(0, $Path.lastIndexOf("\")) + "\old"
            }
        } else {
            return 'No path provided or access has been denied.'
        }
    } end {
        $Excel.Quit()
        $Excel = $null
        [gc]::collect()
        [gc]::WaitForPendingFinalizers()
    }
}