add value_is_required, add logic for sync of clearer on !required attrs

1 files changed, 42 insertions, 13 deletions

diff --git a/lib/Reaction/UI/ViewPort/Field/Role/Mutable.pm b/lib/Reaction/UI/ViewPort/Field/Role/Mutable.pm
index 8690603..cb48dce 100644
--- a/lib/Reaction/UI/ViewPort/Field/Role/Mutable.pm
+++ b/lib/Reaction/UI/ViewPort/Field/Role/Mutable.pm
@@ -9,10 +9,28 @@ role Mutable, which {
   has model     => (is => 'ro', isa => Action, required => 1);
   has attribute => (is => 'ro', isa => ParameterAttribute, required => 1);
 
-  has value      => (is => 'rw', lazy_build => 1, trigger_adopt('value'));
+  has value      => (
+    is => 'rw', lazy_build => 1, trigger_adopt('value'),
+    clearer => 'clear_value',
+  );
   has needs_sync => (is => 'rw', isa => 'Int', default => 0);
   has message    => (is => 'rw', isa => 'Str');
 
+  around value => sub {
+    my $orig = shift;
+    my $self = shift;
+    if (@_ && !ref($_[0]) && defined($_[0]) && !length($_[0])) { # ''
+      unless ($self->value_is_required) {
+        return $self->clear_value;
+      }
+    }
+    $self->$orig(@_);
+  };
+
+  after clear_value => sub {
+    shift->needs_sync(1);
+  };
+
   implements adopt_value => as {
     my ($self) = @_;
     $self->needs_sync(1); # if $self->has_attribute;
@@ -22,20 +40,31 @@ role Mutable, which {
     my ($self) = @_;
     return unless $self->needs_sync && $self->has_value;
     my $attr = $self->attribute;
-    my $writer = $attr->get_write_method;
-    confess "No writer for attribute" unless defined($writer);
-
-    my $value = $self->value;
-    if (my $tc = $attr->type_constraint) {
-      $value = $tc->coercion->coerce($value) if ($tc->has_coercion);
-      #my $error = $tc->validate($self->value); # should we be checking against $value?
-      my $error = $tc->validate($value);
-      if (defined $error) {
-        $self->message($error);
-        return;
+
+    if ($self->has_value) {
+      my $value = $self->value;
+      if (my $tc = $attr->type_constraint) {
+        $value = $tc->coercion->coerce($value) if ($tc->has_coercion);
+        #my $error = $tc->validate($self->value); # should we be checking against $value?
+        my $error = $tc->validate($value);
+        if (defined $error) {
+          $self->message($error);
+          return;
+        }
+      }
+      my $writer = $attr->get_write_method;
+      confess "No writer for attribute" unless defined($writer);
+      $self->model->$writer($value);
+    } else {
+      my $predicate = $attr->get_predicate;
+      confess "No predicate for attribute" unless defined($predicate);
+      if ($self->model->$predicate) {
+        my $clearer = $attr->get_clearer;
+        confess "${predicate} returned true but no clearer for attribute"
+          unless defined($clearer);
+        $self->model->$clearer;
       }
     }
-    $self->model->$writer($value);
     $self->needs_sync(0);
   };