polymorphic_type for STI associations


Currently polymorphic_type field always use the class name of parent
in case of STI.

For example,

I ran into this when I was doing some polymorphic/sti stuff, and it
took me a while to find the documentation describing the solution[1].
I'm no expert, so please forgive me, but this wasn't expected the
behavior I expected, at least :slight_smile:

So, I'd be curious to hear why things were implemented this way as

[1] http://api.rubyonrails.org/classes/ActiveRecord/Associations/ClassMethods.html

- Trevor

I think it's so you can join onto the correct table easily and without
redundancy, since the child type no longer corresponds to anything in
the schema.