Transition from ghost boolean column to user_type

Part 1: double write for ghost attribute

app/models/user.rb

@@ -612,7 +612,7 @@ class User < ApplicationRecord
     # owns records previously belonging to deleted users.
     def ghost
       email = 'ghost%s@example.com'
-      unique_internal(where(ghost: true), 'ghost', email) do |u|
+      unique_internal(where(ghost: true, user_type: :ghost), 'ghost', email) do |u|
         u.bio = _('This is a "Ghost User", created to hold all issues authored by users that have since been deleted. This user cannot be removed.')
         u.name = 'Ghost User'
       end
@@ -650,6 +650,13 @@ class User < ApplicationRecord
     ghost? || bot?
   end
 
+  # We are transitioning from ghost boolean column to user_type
+  # so we need to read from old column for now
+  # @see https://gitlab.com/gitlab-org/gitlab/-/issues/210025
+  def ghost?
+    ghost
+  end
+
   def self.internal
     where(ghost: true).or(bots)
   end

app/models/user_type_enums.rb

@@ -2,13 +2,11 @@
 
 module UserTypeEnums
   def self.types
-    bots.merge(human: nil)
+    @types ||= bots.merge(human: nil, ghost: 5)
   end
 
   def self.bots
-    {
-      alert_bot: 2
-    }.with_indifferent_access
+    @bots ||= { alert_bot: 2 }.with_indifferent_access
   end
 end
 

changelogs/unreleased/210025-migrate-ghost-to-user-type.yml

+---
+title: Fill user_type for ghost users
+merge_request: 27387
+author:
+type: other

db/migrate/20200313101649_fill_ghost_user_type.rb

+# frozen_string_literal: true
+
+class FillGhostUserType < ActiveRecord::Migration[6.0]
+  DOWNTIME = false
+
+  def up
+    execute('UPDATE users SET user_type = 5 WHERE ghost IS TRUE AND user_type IS NULL')
+  end
+
+  def down
+    execute('UPDATE users SET user_type = NULL WHERE ghost IS TRUE AND user_type IS NOT NULL')
+  end
+end

ee/app/models/ee/user_type_enums.rb

@@ -9,12 +9,12 @@ module EE
 
       override :types
       def types
-        super.merge(service_user: 4)
+        @types ||= super.merge(service_user: 4)
       end
 
       override :bots
       def bots
-        super.merge(support_bot: 1, visual_review_bot: 3)
+        @bots ||= super.merge(support_bot: 1, visual_review_bot: 3)
       end
     end
   end

spec/models/user_spec.rb

@@ -3134,6 +3134,8 @@ describe User, :do_not_mock_admin_mode do
       expect(ghost).to be_persisted
       expect(ghost.namespace).not_to be_nil
       expect(ghost.namespace).to be_persisted
+      expect(ghost.user_type).to eq 'ghost'
+      expect(ghost.ghost).to eq true
     end
 
     it "does not create a second ghost user if one is already present" do