fix for deflation of undef value, from ether's pull request 122

lib/HTML/FormHandler/Field.pm

@@ -676,13 +676,15 @@ sub fif {
     {
         return defined $lresult->input ? $lresult->input : '';
     }
-    if ( defined $lresult->value ) {
+    if ( $lresult->has_value ) {
+        my $value;
         if( $self->_can_deflate ) {
-            return $self->_apply_deflation($lresult->value);
+            $value = $self->_apply_deflation($lresult->value);
         }
         else {
-            return $lresult->value;
+            $value = $lresult->value;
         }
+        return ( defined $value ? $value : '' );
     }
     elsif ( defined $self->value ) {
         # this is because checkboxes and submit buttons have their own 'value'

t/infl_defl/undef_deflation.t

@@ -0,0 +1,35 @@
+use strict;
+use warnings;
+use Test::More;
+
+{
+    package MyApp::Form::Test;
+    use HTML::FormHandler::Moose;
+    extends 'HTML::FormHandler';
+
+    has_field 'foo' => ( deflate_method => \&deflate_foo );
+    has_field 'bar';
+
+    sub deflate_foo {
+        my ( $self, $value ) = @_;
+        if ( ! defined $value ) {
+            $value = 'deflated';
+        }
+        return $value;
+    }
+
+}
+
+my $form = MyApp::Form::Test->new;
+ok( $form );
+
+my $init_obj = {
+   foo => undef,
+   bar => 'somebar',
+};
+
+$form->process( init_object => $init_obj, params => {} );
+my $fif = $form->fif;
+is_deeply( $fif, { foo => 'deflated', bar => 'somebar' }, 'undef value was deflated' );
+
+done_testing;