sub _has_one {
my ($class, $join_type, $rel, $f_class, $cond, $attrs) = @_;
+ eval "require $f_class";
unless (ref $cond) {
my ($pri, $too_many) = keys %{ $class->_primaries };
$class->throw( "might_have/has_one can only infer join for a single primary key; ${class} has more" )