Change metadata of pdf file with pypdf2

Question

I want to add a metadata key-value pair to the metadata of a pdf file.

I found a several years old answer, but I think this is way to complicated. I guess there is a

Answer 1

Building on what Cyril N. stated, the code works fine, but it creates a lot of "trash" files since now you have the original file and the file with the metadata.

I changed the code a bit since I will run this on hundreds of files a day, and don't want to deal with the additional clean-up:

from PyPDF2 import PdfFileReader, PdfFileWriter

fin = open('your_original.pdf', 'rb')
reader = PdfFileReader(fin)
writer = PdfFileWriter()

writer.appendPagesFromReader(reader)
metadata = reader.getDocumentInfo()
writer.addMetadata(metadata)

# Write your custom metadata here:
writer.addMetadata({
    '/Title': 'this'
})

fout = open('your_original.pdf', 'ab') #ab is append binary; if you do wb, the file will append blank pages
writer.write(fout)

fin.close()
fout.close()

If you do want to have it as a new file, just use a different name for the pdf in fout and keep ab. If you use wb, you will append blank pages equal to your original file.