Custom order checkout_flow not transitioning

[waaux]

Order checkout flow is not transitioning when I have a order decorator file in my app folder.

   # app/models/spree/order_decorator.rb
   Spree::Order.class_eval do
       checkout_flow do
           go_to_state :payment, if: ->(order) { order.payment? || order.payment_required? }
           go_to_state :complete
        end
   end

It only works when I move the order decorator file to lib folder and require the file in initializers folder.

   # lib/models/spree/order_decorator.rb
   Spree::Order.class_eval do
       checkout_flow do
           go_to_state :payment, if: ->(order) { order.payment? || order.payment_required? }
           go_to_state :complete
        end
   end
 
  # config/initializers/spree.rb
  require "#{Rails.root}/lib/models/spree/order_decorator"

Environment

• Version used: Spree 3.3.6
  *Ruby version: 2.5.3
  *Rails version: 5.1.7

In application.rb

      # config/application.rb
       config.to_prepare do
            # Load application's model / class decorators
           Dir.glob(File.join(File.dirname(__FILE__), "../app/**/*_decorator*.rb")) do |c|
            Rails.configuration.cache_classes ? require(c) : load(c)
           end

           # Load application's view overrides
           Dir.glob(File.join(File.dirname(__FILE__), "../app/overrides/*.rb")) do |c|
            Rails.configuration.cache_classes ? require(c) : load(c)
           end
       end

[waaux]

This is exactly what is happening to my custom checkout flow.
[Cannot transition state via :next from :cart (Reason(s): State is not included in the list) #7337]

How can I fixed this issue with the state machine?

[waaux]

When I do this in my order_decorator.rb I can see my custom checkout flow but for some reason the Order always has state = cart. The order never transition.

   # app/models/spree/order_decorator.rb
    Spree::Order.class_eval do
        remove_checkout_step :address
        remove_checkout_step :delivery
        remove_checkout_step :confirm   
    end

Result:

      {
           "id": 279,
           "number": "R542295901",
            "state": "cart",
            "checkout_steps": [
                "payment",
                "complete"
            ]
     }

[jaredcwhite]

@waaux Thanks for that initial workaround — I was tearing my hair out and I tried your solution and it works! I'm upgrading an old Rails app to Spree 3.6.6 and ran into this issue. So strange that requiring it via a separate file in lib works and inside the main decorator itself it doesn't.