http://github.com/jkraemer/pdf-forms/
by Jens Kraemer, [email protected]

Fill out PDF forms with pdftk (www.accesspdf.com/pdftk/).

require 'pdf_forms'
fdf = PdfForms::Fdf.new :key => 'value', :other_key => 'other value'
# use to_pdf_data if you just want the fdf data, without writing it to a file
puts fdf.to_pdf_data
# write fdf file
fdf.save_to 'path/to/file.fdf'

# To generate XFDF instead of FDF instantiate PdfForms::XFdf instead of PdfForms::Fdf

First get pdftk from www.accesspdf.com/pdftk/ and install it.

require 'pdf_forms'

# adjust the pdftk path to suit your pdftk installation
# add :data_format => 'XFdf' option to generate XFDF instead of FDF when
# filling a form (XFDF is supposed to have better support for non-western
# encodings)
# add :utf8_fields => true in order to get UTF8 encoded field metadata (this
# will use dump_data_fields_utf8 instead of dump_data_fields in the call to
# pdftk)
pdftk = PdfForms.new('/usr/local/bin/pdftk')

# find out the field names that are present in form.pdf
pdftk.get_field_names 'path/to/form.pdf'

# take form.pdf, set the 'foo' field to 'bar' and save the document to myform.pdf
pdftk.fill_form '/path/to/form.pdf', 'myform.pdf', :foo => 'bar'

# optionally, add the :flatten option to prevent editing of a filled out form
pdftk.fill_form '/path/to/form.pdf', 'myform.pdf', {:foo => 'bar'}, :flatten => true

$ gem install pdf-forms

$ git clone http://github.com/jkraemer/pdf-forms.git

The FDF generation part is a straight port of Steffen Schwigon’s PDF::FDF::Simple perl module. Didn’t port the FDF parsing, though ;-)

see LICENSE