Combining CSV files in Powershell - different headings - powershell

Question

I need to take a slew of csv files from a directory and get them into an array in Powershell (to eventually manipulate and write back to a CSV).
The problem is there are 5 file types. I need around 8 columns from each. The columns are essentially the same, but have different headings.
Is there an easy way to do this? I started creating a custom object with my 8 fields, looping through the files importing each one, looking at the filename (which tells me the column names I need) and then a bunch of ifs to add it to my custom object array.
I was wondering if there is a simpler way...like with a template saying which columns from each file.

Answer 1

wound up doing this. It may have not been the most efficient, but works. I wound up writing out each file separately and combining at the end as PS really got bogged down (over a million rows combined).
$Newcsv = #()
$path = "c:\scrap\BWFILES\"
$files = gci -path $path -recurse -filter *.csv | Where-Object { ! ($_.psiscontainer) }
$counter=1
foreach($file in $files)
{
$csv = Import-Csv $file.FullName
if ($file.Name -like '*SAV*')
{
$Newcsv = $csv | Select-Object #{Name="PRODUCT";Expression={"SV"}},DMBRCH,DMACCT,DMSHRT
}
if ($file.Name -like '*TIME*')
{
$Newcsv = $csv | Select-Object #{Name="PRODUCT";Expression={"TM"}},TMBRCH,TMACCT,TMSHRT
}
if ($file.Name -like '*TRAN*')
{
$Newcsv = $csv | Select-Object #{Name="PRODUCT";Expression={"TR"}},DMBRCH,DMACCT,DMSHRT
}
if ($file.Name -like '*LN*')
{
$Newcsv = $csv | Select-Object #{Name="PRODUCT";Expression={"LN"}},LNBRCH,LNNOTE,LNSHRT
}
$Newcsv | Export-Csv "C:\scrap\$file.name$counter.csv" -force -notypeinformation
$counter++
}
get-childItem "c:\scrap\*.csv" | foreach {
$filePath = $_
$lines = $lines = Get-Content $filePath
$linesToWrite = switch($getFirstLine) {
$true {$lines}
$false {$lines | Select -Skip 1}
}
$getFirstLine = $false
Add-Content "c:\scrap\combined.csv" $linesToWrite
}

Answer 2

With a hashtable for reference, a little RegEx matching, and using the automatic variable $Matches in a ForEach-Object loop (alias % used) that could all be shortened to:
$path = "c:\scrap\BWFILES\"
$Reference = #{
'SAV' = 'SV'
'TIME' = 'TM'
'TRAN' = 'TR'
'LN'='LN'
}
Set-Content -Value "PRODUCT,BRCH,ACCT,SHRT" -Path 'c:\scrap\combined.csv'
gci -path $path -recurse -filter *.csv | Where-Object { !($_.psiscontainer) -and $_.Name -match ".*(SAV|TIME|TRAN|LN).*"}|%{
$Product = $Reference[($Matches[1])]
Import-CSV $_.FullName | Select-Object #{Name="PRODUCT";Expression={$Product}},*BRCH,#{l='Acct';e={$_.LNNOTE, $_.DMACCT, $_.TMACCT|?{$_}}},*SHRT | ConvertTo-Csv -NoTypeInformation | Select -Skip 1 | Add-Content 'c:\scrap\combined.csv'
}
That should produce the exact same file. Only kind of tricky part was the LNNOTE/TMACCT/DMACCT field since obviously you can't just do the same as like *SHRT.