Writing metadata to a pdf using pyobjc

Question

I\'m trying to write metadata to a pdf file using the following python code:

from Foundation import *
from Quartz import *

url = NSURL.fileURLWithPath_(\"test.p         


        

Answer 1

DISCLAIMER: I'm utterly new to Python, but an old hand at PDF.

To avoid smashing all the existing attributes, you need to start attrs with pdfDoc.documentAttributes, not {}. setDocumentAttributes is almost certainly an overwrite rather than a merge (given your output here).

Second, all the PDFDocument*Attribute constants are part of PDFDocument. My Python ignorance is undoubtedly showing, but shouldn't you be referencing them as attributes rather than as bare variables? Like this:

attrs[PDFDocument.PDFDocumentTitleAttribute] = "THIS IS THE TITLE"

That you can assign to PDFDocumentTitleAttribute leads me to believe it's not a constant.

If I'm right, your attrs will have tried to assign numerous values to a null key. My Python is weak, so I don't know how you'd check that. Examining attrs prior to calling pdfDoc.setDocumentAttributes_() should be revealing.

Answer 2

Mark is on the right track, but there are a few peculiarities that should be accounted for.

First, he is correct that pdfdoc.documentAttributes is an NSDictionary that contains the document metadata. You would like to modify that, but note that documentAttributes gives you an NSDictionary, which is immutable. You have to convert it to an NSMutableDictionary as follows:

attrs = NSMutableDictionary.alloc().initWithDictionary_(pdfDoc.documentAttributes())

Now you can modify attrs as you did. There is no need to write PDFDocument.PDFDocumentTitleAttribute as Mark suggested, that one won't work, PDFDocumentTitleAttribute is declared as a module-level constant, so just do as you did in your own code.

Here is the full code that works for me:

from Foundation import *
from Quartz import *

url = NSURL.fileURLWithPath_("test.pdf")
pdfdoc = PDFDocument.alloc().initWithURL_(url)

attrs = NSMutableDictionary.alloc().initWithDictionary_(pdfdoc.documentAttributes())
attrs[PDFDocumentTitleAttribute] = "THIS IS THE TITLE"
attrs[PDFDocumentAuthorAttribute] = "A. Author and B. Author"

pdfdoc.setDocumentAttributes_(attrs)
pdfdoc.writeToFile_("mynewfile.pdf")