In a has_many :through association the join model is automatically created.
But...how the parameters are passed to the model?
For example, if I have
has_many :models2, through => :models
has_many :model1, through => :models
The join model is Model.
and I create a new Model1, how params model1_id and model2_id are
passed to model Model?
I want to manage them in a after_save callback of the join model.
How can I do that?