Trailblazer::Compat

This gem provides a seamless-er™ upgrade from TRB 1.1 to 2.x.

It allows to run both old TRB 1.1 operations along with new or refactored 2.x code in the same application, making it easier to upgrade operation code step-wise (no pun intended!) or add new TRB2 operations, workflows, etc. without having to change the old code.

Installation

Your exisiting application's Gemfile should point to the new trailblazer gem.

gem "trailblazer", ">= 2.0.6"
gem "trailblazer-compat"

In a Rails application, you also need to pull the 1.x line of the trailblazer-rails gem.

gem "trailblazer-rails", ">= 1.0.3"

Upgrade Path / Overview

The complete migration path is documented here.

1. You can keep old TRB1 operations.

   # /app/concepts/song/create.rb
   class Song
     class Create < Trailblazer::Operation
       model Song, :create
       policy Song::Policy, :admin?
   
       contract do
         property :id
         # ...
       end
   
       def process(params)
         validate(params[:song]) do |form|
           form.save
         end
       end
     end
   end
   

2. At any point, you can introduce new TRB2 operations or update old classes by inheriting from Trailblazer::Operation.version(2).

   # /app/concepts/song/create.rb
   class Song
     class Create < Trailblazer::Operation.version(2)
       class Form < Reform::Form
         property :id
         # ...
       end
   
       class New < Trailblazer::Operation.version(2)
         step Model( Song, :new )
         step Policy::Pundit( Song::Policy, :admin? )
         step Contract::Build( constant: Form )
       end
   
       step Nested(New)
       step Contract::Validate( key: :admin )
       step Contract::Persist()
     end
   end
   

3. Should you ever be finished updating your application, simply remove the trailblazer-compat gem from the Gemfile. You can then safely delete .version(2) across all files.

Development Status

The compat gem tries to make the transition to newer versions as painless as possible. However, if you run into any problems specific to your application, please don't hesitate to contact us. Pull requests (even ugly hacks) are appreciated in this gem, and this gem only.