TaskStatus::Transition model

app/models/task_status.rb

@@ -4,6 +4,10 @@ class TaskStatus < ApplicationRecord
   belongs_to :workflow
   has_one :project, through: :workflow
 
+  has_many :from_transitions, class_name: 'TaskStatus::Transition', inverse_of: :from, dependent: :destroy
+  has_many :to_transitions, class_name: 'TaskStatus::Transition', inverse_of: :to, dependent: :destroy
+  has_many :next_statuses, class_name: 'TaskStatus', through: :from_transitions, source: :to
+
   enum :icon, %w[new achived done circle_dash hammer play tool].index_by(&:itself), default: 'new', scopes: false
   enum :color, %w[blue gray yellow green purple pink].index_by(&:itself), default: 'gray', scopes: false
 

app/models/task_status/transition.rb

@@ -0,0 +1,10 @@
+# frozen_string_literal: true
+
+class TaskStatus
+  class Transition < ApplicationRecord
+    self.table_name = 'task_status_transitions'
+
+    belongs_to :from, class_name: '::TaskStatus'
+    belongs_to :to, class_name: '::TaskStatus'
+  end
+end