inverse_of not working as documented

rubyonrails-core
1

Please take a look at this gist http://gist.github.com/395267 .

It seems inverse_of is not working as I expect it to. Or am I missing something here?

Thanks

2

It seems inverse_of is not working as I expect it to. Or am I missing something here?

inverse_of isn't an identity map, it only handles traversing associations. So in your case:

dungeon.traps.map {|t| t.dungeon.object_id }

All those object instances will be the same.

3

Thanks Michael for the clarification.

Any thoughts on should Trap.first.dungeon be blowing up?

- Neeraj

4

Any thoughts on should Trap.first.dungeon be blowing up?

Yes, you want inverse_of=>:traps, not :trap.

5

Should inverse_of work with scopes? For example, the following loads different dungeons:

dungeon.traps.order('id desc').map { |t| t.dungeon.object_id }

6

Should inverse_of work with scopes? For example, the following loads different dungeons:

dungeon.traps.order('id desc').map { |t| t.dungeon.object_id }

The current implementation only does that for the instances on the associations themselves, not for values returned by finders.

If you wanted to investigate making that change you could give it a go, but it's probably a fairly intrusive change and not really suitable for inclusion until 3.1. Of course, who knows, maybe it'd be easy :slight_smile:

7

It looks feasible to pass along a new :inverse option to NamedScope::scope, and further along as a "@inverse_value" variable to Relation. It would need to carry both the association @owner and the name of the owner attribute. In Relation#to_a, it would finally be used on the loaded records.

Another option is to add an :after_load callback, which gets called by Relation#to_a for each loaded record. Seems a bit heavyweight right now, but separates the responsibilities.

Thinking out loud won't get us anywhere. I'll try tinkering with it in the meantime.