NAME
DBIx::Class::SQLMaker::Role::SQLA2Passthrough - A test of future possibilities
SYNOPSIS
select and group_by options are processed using the richer SQLA2 code
expand_join_condition is provided to more easily express rich joins
See examples/sqla2passthrough.pl
for a small amount of running code.
SETUP
(on_connect_call => sub {
my ($storage) = @_;
$storage->sql_maker
->with::roles('DBIx::Class::SQLMaker::Role::SQLA2Passthrough');
})
expand_join_condition
__PACKAGE__->has_many(minions => 'Blah::Person' => sub {
my ($args) = @_;
$args->{self_resultsource}
->schema->storage->sql_maker
->expand_join_condition(
$args
);
});
on
__PACKAGE__->has_many(minions => 'Blah::Person' => on {
{ 'self.group_id' => 'foreign.group_id',
'self.rank' => { '>', 'foreign.rank' } }
});
Or with ParameterizedJoinHack,
__PACKAGE__->parameterized_has_many(
priority_tasks => 'MySchema::Result::Task',
[['min_priority'] => sub {
my $args = shift;
return +{
"$args->{foreign_alias}.owner_id" => {
-ident => "$args->{self_alias}.id",
},
"$args->{foreign_alias}.priority" => {
'>=' => $_{min_priority},
},
};
}],
);
becomes
__PACKAGE__->parameterized_has_many(
priority_tasks => 'MySchema::Result::Task',
[['min_priority'] => on {
{ 'foreign.owner_id' => 'self.id',
'foreign.priority' => { '>=', { -value => $_{min_priority} } } }
}]
);
Note that foreign/self can appear in such a condition on either side, BUT if you want DBIx::Class to be able to use a join-less version you must ensure that the LHS is all foreign columns, i.e.
on {
+{
'foreign.x' => 'self.x',
'self.y' => { -between => [ 'foreign.y1', 'foreign.y2' ] }
}
}
is completely valid but DBIC will insist on doing a JOIN even if you have a fully populated row object to call search_related
on - to avoid the spurious JOIN, you must specify it with explicit LHS foreign cols as:
on {
+{
'foreign.x' => 'self.x',
'foreign.y1' => { '<=', 'self.y' },
'foreign.y2' => { '>=', 'self.y' },
}
}