Merge branch '28695-move-all-associated-records-to-ghost-user' into 'master'

Resolve "Deleting a user shouldn't delete associated records"

Closes #28695 and #30514

See merge request !10467

5 files changed, 71 insertions, 20 deletions

diff --git a/app/models/award_emoji.rb b/app/models/award_emoji.rb
index 6937ad3bdd9..6ada6fae4eb 100644
--- a/app/models/award_emoji.rb
+++ b/app/models/award_emoji.rb
@@ -3,13 +3,14 @@ class AwardEmoji < ActiveRecord::Base
   UPVOTE_NAME   = "thumbsup".freeze
 
   include Participable
+  include GhostUser
 
   belongs_to :awardable, polymorphic: true
   belongs_to :user
 
   validates :awardable, :user, presence: true
   validates :name, presence: true, inclusion: { in: Gitlab::Emoji.emojis_names }
-  validates :name, uniqueness: { scope: [:user, :awardable_type, :awardable_id] }
+  validates :name, uniqueness: { scope: [:user, :awardable_type, :awardable_id] }, unless: :ghost_user?
 
   participant :user
 
diff --git a/app/models/concerns/ghost_user.rb b/app/models/concerns/ghost_user.rb
new file mode 100644
index 00000000000..da696127a80
--- /dev/null
+++ b/app/models/concerns/ghost_user.rb
@@ -0,0 +1,7 @@
+module GhostUser
+  extend ActiveSupport::Concern
+
+  def ghost_user?
+    user && user.ghost?
+  end
+end
diff --git a/app/models/user.rb b/app/models/user.rb
index c358b1b8d2b..87eeee204f8 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -89,7 +89,8 @@ class User < ActiveRecord::Base
   has_many :subscriptions,            dependent: :destroy
   has_many :recent_events, -> { order "id DESC" }, foreign_key: :author_id,   class_name: "Event"
   has_many :oauth_applications, class_name: 'Doorkeeper::Application', as: :owner, dependent: :destroy
-  has_one  :abuse_report,             dependent: :destroy
+  has_one  :abuse_report,             dependent: :destroy, foreign_key: :user_id
+  has_many :reported_abuse_reports,   dependent: :destroy, foreign_key: :reporter_id, class_name: "AbuseReport"
   has_many :spam_logs,                dependent: :destroy
   has_many :builds,                   dependent: :nullify, class_name: 'Ci::Build'
   has_many :pipelines,                dependent: :nullify, class_name: 'Ci::Pipeline'
diff --git a/app/services/users/destroy_service.rb b/app/services/users/destroy_service.rb
index a3b32a71a64..ba58b174cc0 100644
--- a/app/services/users/destroy_service.rb
+++ b/app/services/users/destroy_service.rb
@@ -26,7 +26,7 @@ module Users
         ::Projects::DestroyService.new(project, current_user, skip_repo: true).execute
       end
 
-      move_issues_to_ghost_user(user)
+      MigrateToGhostUserService.new(user).execute
 
       # Destroy the namespace after destroying the user since certain methods may depend on the namespace existing
       namespace = user.namespace
@@ -35,22 +35,5 @@ module Users
 
       user_data
     end
-
-    private
-
-    def move_issues_to_ghost_user(user)
-      # Block the user before moving issues to prevent a data race.
-      # If the user creates an issue after `move_issues_to_ghost_user`
-      # runs and before the user is destroyed, the destroy will fail with
-      # an exception. We block the user so that issues can't be created
-      # after `move_issues_to_ghost_user` runs and before the destroy happens.
-      user.block
-
-      ghost_user = User.ghost
-
-      user.issues.update_all(author_id: ghost_user.id)
-
-      user.reload
-    end
   end
 end
diff --git a/app/services/users/migrate_to_ghost_user_service.rb b/app/services/users/migrate_to_ghost_user_service.rb
new file mode 100644
index 00000000000..1e1ed1791ec
--- /dev/null
+++ b/app/services/users/migrate_to_ghost_user_service.rb
@@ -0,0 +1,59 @@
+# When a user is destroyed, some of their associated records are
+# moved to a "Ghost User", to prevent these associated records from
+# being destroyed.
+#
+# For example, all the issues/MRs a user has created are _not_ destroyed
+# when the user is destroyed.
+module Users
+  class MigrateToGhostUserService
+    extend ActiveSupport::Concern
+
+    attr_reader :ghost_user, :user
+
+    def initialize(user)
+      @user = user
+    end
+
+    def execute
+      # Block the user before moving records to prevent a data race.
+      # For example, if the user creates an issue after `migrate_issues`
+      # runs and before the user is destroyed, the destroy will fail with
+      # an exception.
+      user.block
+
+      user.transaction do
+        @ghost_user = User.ghost
+
+        migrate_issues
+        migrate_merge_requests
+        migrate_notes
+        migrate_abuse_reports
+        migrate_award_emoji
+      end
+
+      user.reload
+    end
+
+    private
+
+    def migrate_issues
+      user.issues.update_all(author_id: ghost_user.id)
+    end
+
+    def migrate_merge_requests
+      user.merge_requests.update_all(author_id: ghost_user.id)
+    end
+
+    def migrate_notes
+      user.notes.update_all(author_id: ghost_user.id)
+    end
+
+    def migrate_abuse_reports
+      user.reported_abuse_reports.update_all(reporter_id: ghost_user.id)
+    end
+
+    def migrate_award_emoji
+      user.award_emoji.update_all(user_id: ghost_user.id)
+    end
+  end
+end