How do I most efficiently move, rename files and log this action? - powershell

Question

I have the following CSV list (in reality 1000s of lines):
needle,code
123456,AB
121212,BB
33333333,CVV
And I have a directory (C:\old_files) containing PDF files (again, 1000s in reality):
dsadsadsa.343222.dsads23213jkjl.saddsa.pdf
dsadsadsa.123456.dsads23213jkjl.saddsa.pdf
dsadsadsa.111111.dsads23213jkjl.saddsa.pdf
dsadsadsa.33333333.dsads23213jkjl.saddsa.pdf
dsadsadsa.33333333.fsdgdsfdsfdsf.dsad.pdf
For each needle in the CSV:
I have to see if there is a PDF containing that needle (there might be 0 or more matches)
If there is a match, I have to
make a copy of the file into a separate folder (D:\new_files)
rename the copied file by prepending the respective code to the name
write an entry into the log.
For the example, I have a match for 123456 and 2 for 33333333, so I have to move a copy of these files into D:\new_files and rename them into:
AB.dsadsadsa.123456.dsads23213jkjl.saddsa.pdf
CVV.dsadsadsa.33333333.dsads23213jkjl.saddsa.pdf
CVV.dsadsadsa.33333333.fsdgdsfdsfdsf.dsad.pdf
The logfile would look like (format needle,code,oldfilepath,newfilepath):
123456,AB,C:\old_files\dsadsadsa.123456.dsads23213jkjl.saddsa.pdf,D:\new_files\AB.dsadsadsa.123456.dsads23213jkjl.saddsa.pdf
33333333,CVV,C:\old_files\dsadsadsa.33333333.dsads23213jkjl.saddsa.pdf,D:\new_files\CVV.dsadsadsa.33333333.dsads23213jkjl.saddsa.pdf
33333333,CVV,C:\old_files\dsadsadsa.33333333.fsdgdsfdsfdsf.dsad.pdf,D:\new_files\CVV.dsadsadsa.33333333.fsdgdsfdsfdsf.dsad.pdf
It is important that I only loop over the files in the directory once, because iterating through all files in a ForEach loop for each needle takes way too long. So with thanks to this forum I'm building a hashtable first:
$pairs = #{}
Import-CSV .\data.csv | ForEach-Object { $pairs[$_.needle] = $_.code+"." }
Get-ChildItem "C:\old_files" | Rename-Item -NewName { "D:\new_files\" + $pairs[$_.Name.Split('.')[1]] + $_.Name }
My first problem here: I am unable to move the file into the new folder.
Q1 How do I properly copy a file from C:\old_files into D:\new_files and rename it?
My second problem: I don't understand how I can add code to the above code.
Q2 How can I create the logfile for each match (and therefore: copied and renamed file)?

Answer 1

You need to actually check if you have a match before copying the matching file.
Get-ChildItem "C:\old_files" | ForEach-Object {
$n = ($_.Name -split '.')[1]
if ($pair[$n]) {
$oldname = $_.FullName
$newname = Join-Path 'C:\new_files' ($pair[$n] + $_.Name)
Copy-Item $oldname $newname
}
}
Do the logging after the copy operation:
Copy-Item $oldname $newname
if ($?) {
# log success information here
} else {
# log error information here
}