history.md

Keeping Details History When Changing CanBe Types

CanBe provides a history facility that will allow the details data to be preserved when switching between CanBe types. This way if you switch back to a CanBe type that was previously used, the specific data for the new CanBe type will still be available.

Database Migrations

To implement this history facility, there are no modifications necessary to your existing CanBe tables. You will only need to create a table (via migration) that will store the references for the CanBe types. All of the attribute (column) names must be named as shown in the example below.

create_table :address_can_be_histories, :force => true do |t|
  t.integer :can_be_model_id
  t.string :can_be_type
  t.integer :can_be_details_id
  t.string :can_be_details_type
  t.timestamps
end

NOTE: Examples of the database migrations can be found in the spec/support/schema.rb file.

Models

There are only a few changes that are required to wire up the history model to the CanBe and CanBe details models.

First, you must create an Active Record model for the history table.

class AddressHistory < ActiveRecord::Base
end

CanBe Model

You will have to tell your current CanBe model to use the history model that you defined by adding a call to the #keep_history_in method.

class Address < ActiveRecord::Base
  can_be :home_address, :work_address, :vacation_address do
    add_details_model :home_address, :home_address_detail
    keep_history_in :address_history
  end
end

CanBe Details Models

For each of the details models, you will also have to pass in the history model when calling the #can_be_detail method.

class HomeAddressDetail < ActiveRecord::Base
  can_be_detail :address, history_model: :address_history
end

NOTE: If you also want to change the details_name for the CanBe model, you will also need to specify that in the options parameter of the #can_be_detail method call.

class HomeAddressDetail < ActiveRecord::Base
  can_be_detail :address, history_model: :address_history, details_name: :address_details
end

Calling the "change_to" methods

When you are not storing history for a CanBe model and you call a "change_to" method, the details record that is no longer active will be destroyed. However, when you are storing the history, that record will not be destroy by default.

The "change_to" methods can now take in a parameter that, when set to true, will destroy the details record that is no longer active.

Access the CanBe model from an inactive details model

You can access the CanBe model from any details model that is in the database. This is done in the same way as accessing it from the active details model.