byterock

Today in the Moose-Pen I am going to solve a little problem with Moose.

So cleaning up a lot of Moose poop over the last few days and part of that effort is to ensure some of my proposed features with this post. Now I have re-factored that a little today into this sub

 sub _need_condition {

        my $self = shift;

        my ($action,$required) = @_;

        my $is_required = $required || 0;


        die "Attempt to $action without condition"

          if (

            $is_required

            and

            ( $self->condition_count() + $self->dynamic_condition_count() <= 0 )

          );

   }

and now I still have these attributes to code in

• no_create


• no_retrieve


• no_update


• no_delete


• retrieve_only

So I started with this sub

   sub _cannot_flag {

      my $self = shift;

      my ($action,$cannot,$flag) = @_;

      die "Attempt to $action with $flag Flag on!"

        if ($cannot);

   }

and call it like this

$self->_cannot_flag(Database::Accessor::Constants::DELETE,$self->no_delete(),"no_delete");

and my test is simple enough

  $in_hash->{no_delete} = 1;

  $da = Database::Accessor->new($in_hash);

  eval {  

    $da->delete( $data, $return_str );

  };

  ok ($@,'No Delete with no_delete flag');

The problems comes with the 'retrieve_only' flag. I still get a fail with this test

  delete($in_hash->{no_delete});

  $in_hash->{retrieve_only} = 1;

  $da = Database::Accessor->new($in_hash);

  eval {  

   $da->delete( $data, $return_str );

  };

  ok ($@,'No Delete with retrieve_only flag');

but the real problem is my $@ is going to give me this error

Attempt to DELETE with no_delete Flag on!

Which is true as setting the ' retrieve_only flag' will flip a few other flags, so I might get an error but someone would be rather pissed it they did this

my $in_hash = {

    no_delete => 0,

    retrieve_only=>1,

...  

and spent forty-five mins trying to see why the turn of no_delete is not working.

Now how can Moose help with this? Well Moose can't but a MooseX can.

If I use 'MooseX::MetaDescription' I can extend the meta data of Moose to use a custom value. So to start I need this at the top of my Accessor class

    use Database::Accessor::Constants;

++  use MooseX::MetaDescription;

  

add with my flag attributes like this

has [

        qw(no_create

          no_retrieve

          no_update

          no_delete

          retrieve_only

          )

    ] => ( is => 'ro', 

           isa => 'Bool', 

           default => 0,

 );

  

I will have to break them into individual 'has' commands (a small price to pay) like this

has no_delete=> ( 

           is => 'ro', 

           isa => 'Bool', 

           default => 0,

           traits  => [ 'MooseX::MetaDescription::Meta::Trait' ],

           description =>{message=>"Attempt to use delete with no_delete flag on!"} 

           );

I now have an extra 'meta' attribute on my no_delete class which contains my error message, Now in sub BUILD I add in this little bit of code

       if ($self->retrieve_only){

          foreach my $flag (qw(no_create no_update no_delete)) {

            my $field = $self->meta->get_attribute($flag);

            $field->description->{message} = "No Create, Update or Delete with retrieve_only flag on";

          }

       }

So if my Accessor class has the 'retrieve_only' flag set I iterate over the three other flags get their meta attributes with the 'meta->get_attribute' call then change them for all the same message with the next line.

Now my test will still pass but the message I am getting with $@ is now

No Create, Update or Delete with retrieve_only flag on at...

Moose comes though again.