adds parent_id to threadxs

app/models/threadx.rb

@@ -11,6 +11,7 @@ class Threadx < ActiveRecord::Base
 	has_many :media, :through => :media_threadxes
 
 	belongs_to :owner, :class_name => "User"
+	belongs_to :parent, class_name: 'Threadx', foreign_key: 'parent_id'
 
 	has_many :threadx_collaborators
 	has_many :collaborators, :through => :threadx_collaborators, :source => :user

db/migrate/20180703105721_add_parent_id_to_threads.rb

@@ -0,0 +1,5 @@
+class AddParentIdToThreads < ActiveRecord::Migration
+  def change
+    add_column :threadxes, :parent_id, :integer
+  end
+end

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended to check this file into your version control system.
 
-ActiveRecord::Schema.define(:version => 20140516094821) do
+ActiveRecord::Schema.define(:version => 20180703105721) do
 
   create_table "areas", :force => true do |t|
     t.integer  "x1"
@@ -98,6 +98,7 @@
     t.integer  "owner_id"
     t.datetime "created_at",          :null => false
     t.datetime "updated_at",          :null => false
+    t.integer  "parent_id"
   end
 
   create_table "users", :force => true do |t|