[Dbix-class] Howto convert from DB to Schema

[James FitzGibbon]

I've read over DBIx::Class::Manual::SchemaIntro, but I'm still a bit
confused as to how to move my DB-based set of classes over to Schema.

My current class hierarchy looks like this:

SPE::DA is-a DBIx::Class and loads the 'Core' and 'DB' components at compile
time.  At runtime, it loads PK::Auto::Oracle or PK::Auto::Pg depending on
the DBD in use.  This is shared among multiple projects.  From a discussion
here about a month ago, it is important that the PK::Auto:: component be
more to the left in the inheritance tree than Core and DB in order for
->insert to be overridden properly.

SPE::DA::DCH is for a specific project and is-a SPE::DA.  It has about 10
subclasses (one for each table) in one file, statically defined.

Now, for me to convert to Schema, the docs seem to suggest that there is no
longer a need for SPE::DA.  In the new world, SPE::DA::DCH is-a
DBIx::Class::Schema and uses ->load_classes() to load all the statically
defined subclasses, each of which is-a SPE::DA::DCH.

Each of the subclasses needs to load the Core component.  Now I have to load
the proper PK::Auto component in each of the subclasses of my schema.  I
guess that the best place for this is a method in SPE::DA::DCH, but now I
have to have an initialization subroutine in each of my subclasses and this
in SPE::DA::DCH's initialization:

    {
        no strict 'refs';
        for my $suffix( keys %{$class.'::'} ) {
            next unless( $suffix =~ m/^(.+)::$/ );
            my $subclass = "${class}::" . $1;
            if( UNIVERSAL::isa($subclass, 'UNIVERSAL') &&
$subclass->can('setup') ) {
                $subclass->setup;
            }
        }
    }

(yes, I know that should probably be done using ->sources)

Am I just screwing myself trying to have the same classes work with both
Oracle and PostgreSQL?

Perhaps this isn't a big concern - do most people use
DBIx::Class::Schema::Loader and thus only have the additional classes listed
once in their code?  A long time ago at our local PM meeting, the feeling of
the room was to use ::Loader in development and then switch to statically
defined classes for production (this was using CDBI).  Is that no longer
conventional wisdom?

Is there a concise conversion document I can look at, or should I plod
through and try to create one in the process?

Thanks

-- 
j.
 
James FitzGibbon
Systems Developer, Primus Telecommunications Canada Inc.
416.644.6111

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