sub belongs_to {
my ($class, $rel, $f_class, $cond, $attrs) = @_;
eval "require $f_class";
+ if ($@) {
+ $class->throw($@) unless $@ =~ /Can't locate/;
+ }
+
my %f_primaries;
$f_primaries{$_} = 1 for eval { $f_class->primary_columns };
my $f_loaded = !$@;