[Dbix-class] Inheritance not preserved when using compose_namespace

Matt S Trout dbix-class at trout.me.uk
Mon Sep 24 17:42:40 GMT 2007

On Mon, Sep 24, 2007 at 03:11:28PM +0100, Scott Thomson wrote:
> Hi All,
> I posted a version of this problem on the catalyst list but I now
> think it's more DBIC related so excuse the cross-post :-)
> I have a setup similar to this...
> Class B inherits from class A and class C has a relationship to A.
> A and B share the same table and I use the dynamic sub-classing
> approach in the cookbook to get the sub-classing to work.
> When testing directly with the schema the classes behave as I would
> expect, ie. I can set the value of the relationship on C using an
> object of class either A or B. However, when I use the schema inside
> my Catalyst app I get an error like this when trying to set the
> property using the relationship on A to an object of the sub-class
> C...
> DBIx::Class::MyApp::new(): Object
> MyApp::Model::DBIC::A::B=HASH(0x392b6a0) isn't a MyAPP::Model::DBIC::A
> (The error is generated in
> DBIx::Class::Relationship::Base::set_from_related)
> It seems that the B isa A relationship is not preserved within the
> MyApp::Model namespace.  After some digging around it seems like it is
> the call to compose_namespace in Catalyst::Model::DBIC::Schema::new
> that is causing this behaviour.  Effectively it renames all the schema
> classes into the MyApp::Model namespace and the ISA chain in the new
> namespace is not preserved, so this would affect any schema that is
> generated using the compose_namespace method.
> I'm a bit stumped on how to proceed, I can get round the problem with
> a bit of a hack (basically by not using the relationship to set
> values) but I'm converting a large set of classes to DBIC and this
> problem is going to occur in quite a few places.
> Given the ubiquity of DBIC as a model for Catalyst I'm quite surprised
> that no-one has come up against this before - which may mean that it's
> something that I'm doing wrong  :-)

No, that's a bug.

I guess compose_namespace should look for classes its composing in the
inheritance tree and swap 'em for the composed version.

Anybody up for having a go at a test+patch?

      Matt S Trout       Need help with your Catalyst or DBIx::Class project?
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