Tie existing data

to support add_mapping_resolver and on_create

lib/YAML/PP/Constructor.pm

@@ -139,7 +139,7 @@ sub mapping_start_event {
     my $preserve_style = $self->preserve_flow_style;
     my $preserve_alias = $self->preserve_alias;
     if (($preserve_order or $preserve_style or $preserve_alias) and not tied(%$data)) {
-        tie %$data, 'YAML::PP::Preserve::Hash';
+        tie %$data, 'YAML::PP::Preserve::Hash', %$data;
     }
     if ($preserve_style) {
         my $t = tied %$data;

t/41.custom.schema.t

@@ -3,23 +3,37 @@ use strict;
 use warnings;
 use Test::More;
 use YAML::PP;
+use YAML::PP::Common qw/ :PRESERVE /;
 
 use FindBin '$Bin';
 use lib "$Bin/lib";
 
 my $yp = YAML::PP->new(
     schema => [qw/ :MySchema /],
+    preserve => PRESERVE_ORDER,
 );
 
-my $data = {
-  o1 => (bless {}, 'Class1'),
-};
+my $yaml = <<'EOM';
+---
+o1: !Class1
+  z: 1
+  a: 2
+  y: 3
+  b: 4
+EOM
+
+my $data = $yp->load_string($yaml);
 
-my $yaml = $yp->dump_string($data);
+$yaml = $yp->dump_string($data);
 
 cmp_ok($yaml, 'eq', <<EOY, '$data serializes with the schema in t/lib/MySchema.pm');
 ---
-o1: !Class1 ''
+o1: !Class1
+  id: 23
+  z: 1
+  a: 2
+  y: 3
+  b: 4
 EOY
 
 done_testing;

t/lib/MySchema.pm

@@ -13,13 +13,22 @@ package MySchema;
     my ($self, %args) = @_;
     my $schema = $args{schema};
 
+    $schema->add_mapping_resolver(
+        tag => '!Class1',
+        on_create => sub { return bless { id => 23 }, 'Class1' },
+        on_data => sub {
+            my ($constructor, $data, $list) = @_;
+            %$$data = (%$$data, @$list);
+        },
+    );
+
     $schema->add_representer(
       class_equals => 'Class1',
       code => sub {
         my ($representer, $node) = @_;
         # $node->{value} contains the object
         $node->{tag} = '!Class1';
-        $node->{ data } = '';
+        $node->{data} = $node->{value};
         return 1;
       },
     );