python-pypdf

name	python-pypdf
description	Guide on using the Python pypdf library to read, write, and fill PDF forms programmatically.

pypdf

The pypdf library allows you to manipulate PDF files in Python. This skill focuses on reading PDF form fields and filling them out programmatically.

Installation

pip install pypdf

Reading PDF Form Fields

You can read all form fields from a PDF to understand their names and types:

from pypdf import PdfReader

reader = PdfReader("form.pdf")
fields = reader.get_fields()

for field_name, field_data in fields.items():
    print(f"Field: {field_name}, Type: {field_data.get('/FT')}, Value: {field_data.get('/V')}")

Filling PDF Forms

You can create a writer object, append the pages from the reader, and then use the update_page_form_field_values method to fill fields:

from pypdf import PdfReader, PdfWriter

reader = PdfReader("form.pdf")
writer = PdfWriter()
writer.append_pages_from_reader(reader)

# Define a dictionary mapping field names to values.
data = {
    "FieldName1": "Value1",
    "Checkbox1": "/Yes"  # Checkboxes usually expect "/Yes" or "/Off"
}

writer.update_page_form_field_values(writer.pages[0], data)

with open("filled.pdf", "wb") as f:
    writer.write(f)