pdf-form-filling

PDF Form Filling with Python

Overview

This skill covers how to identify and fill form fields in PDF documents, particularly for legal forms like court documents.

Key Libraries

1. PyPDF (pypdf)

• Modern, actively maintained library for PDF manipulation
• Can read form field names and fill them
• Installation: pip install pypdf

2. pdfrw

• Lightweight alternative, good for form filling
• Installation: pip install pdfrw

Common Workflow

With pypdf:

from pypdf import PdfReader, PdfWriter

# Read the blank form
reader = PdfReader("/path/to/form.pdf")
writer = PdfWriter()

# Get the form fields
fields = reader.get_fields()
print(fields.keys())  # See all available fields

# Create a copy and update fields
for page in reader.pages:
    writer.add_page(page)

# Update fields
writer.update_page_form_field_values(
    writer.pages[0],
    {
        "Field1": "Value1",
        "Field2": "Value2",
    }
)

# Save the result
with open("/path/to/filled.pdf", "wb") as f:
    writer.write(f)

With pdfrw:

from pdfrw import PdfReader, PdfWriter, PdfDict, PdfObject

# Read template
template = PdfReader("/path/to/form.pdf")

# Inspect available fields
for field in template.Root.AcroForm.Fields:
    print(field.T)  # Field name

# Fill fields
for field in template.Root.AcroForm.Fields:
    if field.T == "FieldName":
        field.V = "Field Value"
        field.AP = None  # Clear appearance stream

# Write output
PdfWriter().write("/path/to/filled.pdf", template)

Inspecting Form Fields

from pypdf import PdfReader

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

for field_name, field_data in fields.items():
    print(f"{field_name}: {field_data}")

Important Notes

• Form field names are case-sensitive
• Some PDFs have checkboxes/radio buttons requiring "Yes"/"No" or specific values
• Date fields may need specific formatting
• Always check field types before filling
• Keep a copy of the blank form for reference