Polymorphic associations and acts_as_xxx

July 26, 2009 at 3:00 pm Leave a comment

There are many plugins that allow you to use Rails’ powerful polymorphic relationship. Basically, polymorphic relationship allows you to create for example a Comments module and link to it from any of your classes by using “acts_as_commentable” declaration. How Comment class will not which object it gets linked to? It simply stores 2 fields in the database – xxx_id and xxx_type.

And what if you want to get an object (for example a post) on which somebody commented? It’s actually quite simple. If @comment stores your comment, then @comment.commentable will be the object on which the comment was made. This principle will work with any other acts_as plugin. For acts_as_voteable, you will need to access vote.voteable, etc.


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