PDF Forms - List and fill fields

This example shows how to list the form fields of an interactive PDF form and how to fill out the form.

The output file from the PDF forms example can be used as input.

One way to list and fill a PDF form is to use the HexaPDF CLI with the ‘form’ command. Here, however, we are doing it with the HexaPDF API.

Usage:: ruby acro_form_list_and_fill.rb [INPUT.PDF]

Code

require 'base64'
require 'hexapdf'

doc = HexaPDF::Document.open(ARGV[0] || 'acro_form.pdf')
exit unless doc.acro_form

puts "Listing all form fields:"
doc.acro_form.each_field do |field|
  puts "#{field.full_field_name} (#{field.concrete_field_type})"
end

# We are using this to generate some values for existing text fields. In the
# real world one would be getting the values from the user.
puts "\nFilling in the text fields with random values:"
values = {}
doc.acro_form.each_field do |field|
  next unless field.field_type == :Tx
  value = Base64.encode64(field.full_field_name).strip
  value = if field.key?(:MaxLen)
            value[0, field[:MaxLen]]
          else
            "Value #{field.field_type} #{value}"
          end
  values[field.full_field_name] = value
  puts "#{field.full_field_name}: #{value}"
end

# Now actually fill out the form the values
doc.acro_form.fill(values)

doc.write('acro_form_list_and_fill.pdf', optimize: true)