Powershell function to use excel to convert between file formats

Question

I have a need to use scheduled tasks or chron jobs to convert files between xlsx and csv and xml and xlsx.

I didn't find anything I loved so I wrote a module to make my life easier.

Initial requirements had me knowing that I had access to static full file names when the job was scheduled. After writing a simple script I expanded it for features I thought might come in handy.

Answer 1

I saved this into a psm1 file and load it with my profile.

Features: Pipeline safe(ish) -flexible outputs -extension option if you like the name but not the file type -delete option in case you want to clean up after yourself

Comments up front create workable help in PowerShell, but are fairly readable too.

<#
.SYNOPSIS
This function will take files and use the excel application to convert them.

.DESCRIPTION
This function allows you to use the full power of Excel to open and save files. The infile can be any file that Excel can open. The outfile can be xlsx, xsl, xml, or csv. Also, there is an option to delete the destination file before runing the save operation to avoid prompts when overwriting, and to erase the origin file after the process has completed.

.EXAMPLE
Convert-Excel -infile 'Source.xml' -outfile 'destination.xlsx' -delete $true
Converts source.xml to xlsx file type.
Deletes source.xml when done.
Deletes destination.xlsx before it converts.

.EXAMPLE
Convert-Excel -infile 'Source.xlsx' -outfile 'destination.csv' 
Converts xlsx to csv.
Leaves both files behind when done.

.EXAMPLE
Convert-Excel -infile 'Source.csv' 
Converts infile Source.csv (or whatever format) to xlsx of the same name.
Leaves both behind when done.

.EXAMPLE
Convert-Excel -infile 'Source.xlsx' -Extension '.csv' 
Converts xlsx to csv. By passing just the extension it will use the same base file name.
Leaves both files behind when done.

.EXAMPLE
Convert-Excel -infile 'C:\Users\notI\PRD-06661-12082017 - Copy.xml' -outfile 'C:\Users\notI\PRD-06661-12082017-Copy.csv'
Loads full path xml
Saves full path csv

.EXAMPLE
dir *.xml | Sort-Object -Property LastWriteTime | Convert-Excel -Extension ".csv"
Similar to above but uses the pipeline to do multiple conversions.
If full outfile name is given, it will create just one file over and over again. In this example it would go in chronological order creating csv files.

.EXAMPLE
Dir *.xml | Convert-Excel -extension ".csv" -delete $True | Convert-Excel -extension ".xml"
Thats just weird, but it might solve your problem, and it works.

.PARAMETER infile
Name of the origin file to use. If the full path is not given it will be opened from the context the script is running in.

.PARAMETER outfile (extension)
Name of the destination file to create. If the full path is not given it will save in the default destination of Excel.

.PARAMETER delete
If $true it will delete the target location file if it exists before conversion and the origin file after conversion. Functions like a move with clobber.
If anything else or blank it will leave origin in place and if destination exists it will prompt for overwriting.
#>
function Convert-Excel{
    param(
        [parameter(ValueFromPipeLineByPropertyName=$True,ValueFromPipeline=$True)]
        [Alias('FullName')]
        [string] $infile,
        [Alias('Extension')]
        [string] $outfile,
        [bool] $delete

    )
    Begin {
        $begin_outfile = $outfile
        Try {$ExcelWB = new-object -comobject excel.application}
        Catch {Write-Host "This host does not seem to have Excel installed"}
    }

    Process{
    #Check infile 
        if (-not($infile)) {
            Write-Output "You must supply a value for -infile"
            break
        }
        else {
            Try {$file = Get-Item $infile}
            Catch {Write-Output "$infile does not seem to exist, or I can't get to it"; break}
        }

    #Check outfile
        #Reset value for pipeline loop            
        $outfile = $begin_outfile

        #If blank just presume xlsx
        if (-not($outfile)) {
            $outfile = $file.FullName -replace '\.[^.]+$',".xlsx"
            Write-Verbose "No outfile supplied, setting outfile to $outfile"
        }

        #If startswith a dot, use as an extension.
        If ($outfile.StartsWith(".")) {
            $outfile = $file.FullName -replace '\.[^.]+$',$outfile
            Write-Verbose "Extension supplied, setting outfile to $outfile"
        }

        #derive XlFileFormat from extension
        if($outfile -cmatch '\.[^.]+$') {
            $extens="" #Reset for pipeline loop
            switch ($Matches[0]) 
            {
                ".xlsx" {$extens = 51}
                ".csv"  {$extens = 6}
                ".xml"  {$extens = 46}
                ".xls"  {$extens = -4143}
                ".xlsm" {$extens = 52}
                default {$extens = 51}
            }

        }
        else {
            break #if it can't find an extension in regex
        }

        if ($file.FullName -eq $outfile) {
            #Nobody needs us to create a copy of an existing file.
            write-verbose "Goal already achieved, moving on"
        }
        Else {
            if(Test-Path ($outfile)){
                #Avoid prompting to overwrite by removing an existing file of the same name
                Remove-Item -path ($outfile)
            }

            Try {
                Write-Verbose "Loop Check $infile"

                if ($file.Extension -eq ".xml") {
                    #Make assumptions for XML. If you need more control don't automate
                    $Workbook = $ExcelWB.Workbooks.OpenXML($file.FullName,1)
                }
                else {
                    #Act Normal
                    $Workbook = $ExcelWB.Workbooks.Open($file.FullName)
                }
                $Workbook.SaveAs($outfile,$extens)
                $Workbook.Close($false)
            }
            Catch {
                Write-Host "Unable to convert file $file because Excel cannot open or save it without help"
                break
            }

            if ($delete) {#If asked to delete
                if(Test-Path ($outfile)){ #And a file now exists where outfile said it should be
                    if(Test-Path ($infile)){ #And there is a file at infile
                        Remove-Item -path ($infile) #Delete it
                    }
                }
            }
            #Mostly to keep from breaking the pipeline, but not bad as an output of a file creator
            Return $outfile
        }
    }
    End{
        #Cleanup
        $ExcelWB.quit()
    }
}
export-modulemember -function Convert-Excel