upgrading_extensions.md

title	section	order
Updating Extensions for Spree 4	contributing	2

Upgrading extensions

Overview

This guide covers the process of migrating an old Spree 2/3 extension to Spree 4.

Zeitwerk compatibility

Zeitwerk is the new default code autoloader in Rails 6.

This doesn't work well with the old approach to decorators (files that name ends with decorator.rb, eg. app/models/spree/order_decorator.rb) using class_eval.

To fix this we need to convert all class_eval decorators to modules and use Module.prepend. Also we need to name them properly according to Zeitwerk naming rules

Example of an old decorator:

app/models/spree/order_decorator.rb

Spree::Order.class_eval do
  has_many :new_custom_model

  def some_method
     # ...
  end
end

the same decorator in the new notation:

app/models/your_extension_name/order_decorator.rb

module YourExtensionName::OrderDecorator
  def self.prepended(base)
    base.has_many :new_custom_model
  end

  def some_method
    # ...
  end
end

::Spree::Order.prepend(YourExtensionName::OrderDecorator)

Travis CI configuration

You can always find up-to-date Travis CI config here: https://github.com/spree/spree/blob/master/cmd/lib/spree_cmd/templates/extension/travis.yml For the rationale of the changes please look at the blame view: https://github.com/spree/spree/blame/master/cmd/lib/spree_cmd/templates/extension/travis.yml

Appraisals config

You can always find up-to-date Appraisals config here: https://github.com/spree/spree/blob/master/cmd/lib/spree_cmd/templates/extension/Appraisals

For the rationale of the changes please look at the blame view: https://github.com/spree/spree/blame/master/cmd/lib/spree_cmd/templates/extension/Appraisals

After each change please remember to re-generate gemfiles by running:

bundle exec appraisal generate --travis

Fixing Deface Overrides

Please remember to prepare versioned overrides for both Spree 3.x and 4.x, eg. https://github.com/spree-contrib/spree_static_content/commit/e4b9e4900024235158d0ec1a48a100b4732348ef

Spree 4 uses Bootstrap 4 and many partials and HTML structure changed compared to Spree 3.x.

Also - remember to add deface gem to gemspec as deface itself was removed as a dependency of Spree. eg. https://github.com/spree/spree_auth_devise/commit/d729689ca87d8586e541ffcc865ef1e0a5a79fe4

Migrate to Spree Dev Tools

Replace all development dependencies with:

s.add_development_dependency 'spree_dev_tools'

Replace spec_helper.rb contents with:

https://github.com/spree/spree/blob/777a284b4c70e69d32a05ffa61bbe3905d8f1297/cmd/lib/spree_cmd/templates/extension/spec/spec_helper.rb

Example migrations:

• spree/spree_gateway#357
• spree-contrib/spree-product-assembly#200
• spree/spree_auth_devise#487