The following migration in Rails 3 works:
class CreateUserActions < ActiveRecord::Migration
def up
create_table :user_actions do |t|
t.datetime :time
t.integer :user_id
t.text :action
t.column :details, :json
t.timestamps
end
end
def down
drop_table 'user_actions'
end
end
...but schema.rb is now incomplete reporting
# Could not dump table "user_actions" because of following StandardError
# Unknown type 'json' for column 'details'
So rake db:reset will fail to create the user_actions table.