How to change class of an STI object?

I have some models which use the same table via single table
inheritance. I (think I) need to change objects from one class to
another and not sure how to go about that.

Consider these models:

  class Project < ActiveRecord::Base

  class Goal < Project # inherits project characteristics

  class Assignment < Project # inherits project characteristics

They are distinguished from each other by the 'type' column.

  class CreateProjects < ActiveRecord::Migration
    def self.up
      create_table :projects do |t|
        t.column :type, :string

How would I convert a 'Project' object into a 'Goal' object while
preserving other characteristics (id, title, etc.)?


Just change the value in the type column to change the type to any of
the other types. I define a method that aliases to type to make it
easier to access. You will need to reload the data to get a different
Ruby object.


Thanks Michael. That's simple enough!