python – Django: How to save pdf file from PdfFileMerger

What wrongs this code? I want to save the file to the field’s model 😭😭

obj = Document.object.first()

merger = PdfFileMerger()
for pdf in (memo_pdf, page_2):
    merger.append(pdf)
merger.write(f'{str(uuid.uuid4())}.pdf')
merger.close()

obj.pdf = merger
obj.save()