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 an easier way today: https://stackoverflow.com/a/3257340/633961

I am not married with pypdf2, if there is an easier way, then I go this way?

Tarun Lalwani

You can do that using pdfrw

pip install pdfrw

Then run

from pdfrw import PdfReader, PdfWriter   
trailer = PdfReader("myfile.pdf")    
trailer.Info.WhoAmI = "Tarun Lalwani"    
PdfWriter("edited.pdf", trailer=trailer).write()

And then check the PDF Custom Properties

Cyril N.

I was surprised to see there is no code sample for PyPDF2 when the questions is explicitly asking for PyPDF2, so here it is:

from PyPDF2 import PdfFileReader, PdfFileWriter

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

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

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

fout = open('result.pdf', 'wb')
writer.write(fout)

fin.close()
fout.close()

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.

The correct way to edit PDF metadata in Python

There are several ways to edit PDF metadata in Python, but one way is better than the others.

I will start by talking about other ways that seem right but have side effects. Skip to the end of this article if you don’t have enough time and just use the correct way.

Weakness is package not maintained.

from pdfrw import PdfReader, PdfWriter, PdfDict

if __name__ == '__main__':
    pdf_reader = PdfReader('old.pdf')
    metadata = PdfDict(Author='Someone', Title='PDF in Python')
    pdf_reader.Info.update(metadata)
    PdfWriter().write('new.pdf', pdf_reader)

pdfrw can do quite easily without losing non-display information such as bookmarks.

PyPDF2 supports more PDF features than pdfrw, including decryption and more types of decompression.

Weakness is PDF not preserve outlines(bookmarks).

import pprint

from PyPDF2 import PdfFileReader, PdfFileWriter

if __name__ == '__main__':
    file_in = open('old.pdf', 'rb')
    pdf_reader = PdfFileReader(file_in)
    metadata = pdf_reader.getDocumentInfo()
    pprint.pprint(metadata)

    pdf_writer = PdfFileWriter()
    pdf_writer.appendPagesFromReader(pdf_reader)
    pdf_writer.addMetadata({
        '/Author': 'Someone',
        '/Title': 'PDF in Python'
    })
    file_out = open('new.pdf', 'wb')
    pdf_writer.write(file_out)

    file_in.close()
    file_out.close()

Using PdfFileWriter create a new PDF, and get old contents through appendPagesFromReader(), then addMetadata().

It seems that we cannot directly modify the PDF metadata, so we add all pages and metadata then write out to a new file.

The correct way to edit PDF metadata in Python.

import pprint

from PyPDF2 import PdfFileReader, PdfFileMerger

if __name__ == '__main__':
    file_in = open('old.pdf', 'rb')
    pdf_reader = PdfFileReader(file_in)
    metadata = pdf_reader.getDocumentInfo()
    pprint.pprint(metadata)

    pdf_merger = PdfFileMerger()
    pdf_merger.append(file_in)
    pdf_merger.addMetadata({
        '/Author': 'Someone',
        '/Title': 'PDF in Python'
    })
    file_out = open('new.pdf', 'wb')
    pdf_merger.write(file_out)

    file_in.close()
    file_out.close()

Using PdfFileMerger concatenate pages through append().

append(fileobj, bookmark=None, pages=None, import_bookmarks=True)