Polymorphic Association / Rails3 Question

Ok,

I have a polymorphic Attachment model which is working okay when it's dependant of a Campaign model. This is working fine:

Campaign.last.attachments

I'm getting all the attachments of that campaign. But, I need to do it the other way around: Retrieve the parent object of an attachment (retrieve the campaign). I imagined it would be something like this.

Attachme开发者_高级运维nt.last.campaign

But I'm getting nil as result. The attachment object has attachable_id: 64, attachable_type: "Campaign".

I'm missing something here but I can't figure it out what.

Thank you!

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If you configured the polymorphic association correctly:

some_attachment.attachable