pyPDF2 to PyMuPDF

[vicrem]

Hi everyone,

Can someone plz explain/show me how I can rewrite following code to work in PyMuPDF? I have tried with widgets but not fully happy.

def sort_fields(self, field):
    
  form = field.get_object().get('/Kids')

  if form:

    return [self.sort_fields(f) for f in form]

  else:

    return (field.get_object().get('/V'))




def main(self):
    
  _pdf = PdfReader(self.pdf_file)
  
  fields = _pdf.trailer['/Root']['/AcroForm']['/Fields']


  for field in fields:
    _data = self.sort_fields(field)
    ...

Thx in advanced
//Victor

[JorjMcKie]

The issue here is that in PyMuPDF fields / widgets are kids of pages. To simulate pypdf2's behavior, one must use PyMuPDF's low-level functions - which still look similar enough to pypdf2.

With the low-level functions, you can access all of a PDF's object directly in a syntax close to PDF source code. So your above code would look like this:

import fitz, sys

def sort_fields(doc, field_xref):  # invoke with a field's cross ref number
    kids = doc.xref_get_key(field_xref, "Kids")  # are there kids?
    if kids[0] == "array":  # extract xref numbers from the kids array
        xrefs = list(map(int, kids[1][1:-1].replace("0 R", "").split()))
        return [sort_fields(doc, i) for i in xrefs]  # return list of kid field values
    return doc.xref_get_key(field_xref, "V")[1]  # return the field value


def main():
    doc = fitz.open("input.pdf")  # open PDF
    root = doc.pdf_catalog()  # access its catalog
    field_xrefs = doc.xref_get_key(root, "AcroForm/Fields")[1]  # extract array of field xref numbers
    if field_xrefs == "null":
        sys.exit("Document has no fields")
    # the array looks like "[4711 0 R 4712 0 R 123 0 R ...]"
    # xref numbers of all fields
    field_xrefs = list(map(int, field_xrefs[1:-1].replace("0 R", "").split()))
    for xref in field_xrefs:
        value = sort_fields(doc, xref)
        print(f"Field {xref} has value '{value}'.")

Note that in PDF, the string "null" represents what is called None in Python.

[vicrem]

Thank you @JorjMcKie! Your code does exactly what I want :) how can I buy you a beer?