I am essentially working toward he same end posted by merlyn some time ago in Filling out PDF forms with data from DBI?. The reply posted in Re^2: Filling out PDF forms with data from DBI? is very helpful, but indicates that for checkboxes:
On this particular form I noticed that the check boxes were not form fields. Randal, does your client require a check mark on the document, e.g. for "sole proprietor" or "Corporation?" The only reason I ask is because I don't see an easy means to add a check mark using CAM::PDF. PDF::API2 or PDF::Reuse can do that easily. However, they don't have the easy interface into forms the way CAM::PDF does. It might be a bit of a kludge, but running through CAM::PDF to fill in the forms and then running through PDF::API2 to add any checkmarks (or any kind of glyphs or graphics) would be pretty easy.

I would like very much to avoid this method of populating checkboxes because it effectively breaks the PDF form -- that is to say that once something is printed over the top of a checkbox it can no longer be operated as a checkbox.

I am not certain if it is because CAM::PDF or the PDF format has changed significantly since then, but getFormFieldList within CAM::PDF actually does return checkbox keys which are (to some degree) accessible through the same CAM::PDF object.

I have used CAM::PDF to access the dictionary objects for these checkboxes using the W-9 at http://www.irs.gov/pub/irs-pdf/fw9.pdf as a test case. I have compared the objects for each checkbox from a form that is saved with and without the boxes checked. The checked boxes appear like so (the following example is from the first checkbox in the form, using Data::Dumper): 
$VAR1 = {
          'FT' => bless( {
                           'value' => 'Btn',
                           'gennum' => '0',
                           'type' => 'label',
                           'objnum' => '31'
                         }, 'CAM::PDF::Node' ),
          'DA' => bless( {
                           'value' => '/ZaDb 9.0 Tf 1.000 0.660 0.000 
+0.180 k
',
                           'gennum' => '0',
                           'type' => 'string',
                           'objnum' => '31'
                         }, 'CAM::PDF::Node' )
        };

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and the checked boxes seem to have a small portion added: 
$VAR1 = {
          'FT' => bless( {
                           'value' => 'Btn',
                           'gennum' => '0',
                           'type' => 'label',
                           'objnum' => '31'
                         }, 'CAM::PDF::Node' ),
          'DA' => bless( {
                           'value' => '/ZaDb 9.0 Tf 1.000 0.660 0.000 
+0.180 k
',
                           'gennum' => '0',
                           'type' => 'string',
                           'objnum' => '31'
                         }, 'CAM::PDF::Node' ),
          'V' => bless( {
                          'gennum' => '0',
                          'value' => 'Yes',
                          'type' => 'label',
                          'objnum' => '31'
                        }, 'CAM::PDF::Node' )
        };

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I have started with the following code that modifies the object to include the missing section, however I am still not seeing it in the form. 
#!/usr/bin/perl
# pdf-filler-test.pl
use strict;
use warnings;
use CAM::PDF;
use Data::Dumper;
my $infile  = 'fw9.pdf';
my $outfile = 'modified_fw9.pdf';
my $pdf     = CAM::PDF->new($infile) or die "Cannot open $infile";
my @FIELDS  = $pdf->getFormFieldList();

use Data::Dumper;
foreach my $field ( @FIELDS ) {
    if ($field =~ /^c/) {
        my $ff_obj    = $pdf->getFormField($field);
        my $dict   = $pdf->getFormFieldDict($ff_obj);
        $dict->{V} = CAM::PDF::Node->new('label', 'Yes', $ff_obj->{obj
+num}, $ff_obj->{gennum});
        print Dumper $dict;
    }
    else {
        $pdf->fillFormFields($field => $field);
    }
}
$pdf->fillFormFields(
        'f1_01(0)' => 'name',
        'f1_02(0)' => 'test',
);
$pdf->cleanoutput($outfile);

[download]
I am not sure if there is just something I am missing or if this really is not feasible, but would gladly welcome suggestions.

In reply to Filling PDF Form Checkboxes by steve

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