Odd. This works fine:

    WebR::M::CDBI::DatafileRelationship->has_a(child=>'WebR::M::CDBI::
+Datafile');
    WebR::M::CDBI::DatafileRelationship->has_a(parent=>'WebR::M::CDBI:
+:Datafile');
    WebR::M::CDBI::Datafile->has_many(parents=>['WebR::M::CDBI::Datafi
+leRelationship' => 'parent'],'child', {
          cascade => 'Class::DBI::Cascade::Delete'});
    WebR::M::CDBI::Datafile->has_many(children=>['WebR::M::CDBI::Dataf
+ileRelationship' => 'child'],'parent', {
          cascade => 'Class::DBI::Cascade::Delete'} );
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Ah - and if I do

    WebR::M::CDBI::DatafileRelationship->has_a(child=>'WebR::M::CDBI::
+Datafile', {cascade=>'Class::DBI::Cascade::Delete'});
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then the child datafiles get deleted too. Great! thanks! And, for the has_many relationships where I just want the FK to be nulled, rather than the record deleted:

package Class::DBI::Cascade::Nullify;

use base 'Class::DBI::Cascade::None';
use Data::Dumper;

sub cascade {
  my ($self, $obj) = @_;


  my $fk =$self->{_rel}->args->{foreign_key};
  foreach ($self->foreign_for($obj)){
    $_->$fk(undef); 
    $_->update;
  }
}

1;
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