[Dbix-class] Relationships spanning multiple databases

[Matt S Trout]

Sam Crawley wrote:
> Hi,
> 
> I have two schemas connecting to two related databases. I'd like some 
> way of "joining" between the two, i.e. to be able to do this:
> 
> my $record = App::Schema1::RS->find(1);
> 
> my $rec2 = $record->rec_from_schema2;
> 
> Where $rec2 is something from Schema2, i.e. data from a different database.
> 
> I thought I may be able to setup a relationship from one schema to the 
> other, and DBIC would just DWIM, e.g.
> 
> App::Schema1::RS->belongs_to( 'rec_from_schema2' => 'App::Schema2::RS', 
> 'fk');

That's undwimmable - DBIC has no way of knowing what $schema object to use on 
the other side, and a relationship in DBIC is expected to be a "proper" DB 
relationship, i.e. one you can join on.

> Is there any way I can roll my own?

Use inflate_column - this is why where CDBI (which doesn't know what a JOIN 
is) has has_a for both FKs and inflates, DBIC keeps belongs_to and 
inflate_column separate.

Of course, if your databases were in the same DBMS you could potentially join 
it properly - mysql people use ->table('dbname.tblname') just fine, similarly 
with real databases and multiple schemas