Question

I have two class that are linked on

foreign.weirdkey => substr(self.key, 1, 9)

…and cannot for the life of me figure out how to construct the has_many call to indicate this.

The underlying database (a set of Oracle tables) defines no foreign keys, is fixed, and is outside of my control.

I’ve been through the docs and can’t seem to find a syntax that will work within the confines of a manual has_many definition.

Any help would be much appreciated.

Answer 1

something like this should work:

__PACKAGE__->has_many( baubles => 'My::Schema::Result::Thing', sub {
   my $args = shift;

   return ({
      "$args->{foreign_alias}.weirdkey" => \"substr($args->{self_alias}.key, 1, 9)",
   },
   $args->{self_rowobj} && {
      "$args->{foreign_alias}.weirdkey" => substr($args->{self_rowobj}->key, 1, 9)
   })
});

Note that I use perl’s substr if you have the current row object, so then the join will collapse into merely a where clause and won’t use the database for the string munging. Remove that or fiddle with it if you have problems. DBIC_TRACE should make it clear what goes on.

Documentation here: https://metacpan.org/pod/DBIx::Class::Relationship::Base#condition