1 files changed, 22 insertions, 0 deletions
diff --git a/lib/gitlab/background_migration/fix_promoted_epics_discussion_ids.rb b/lib/gitlab/background_migration/fix_promoted_epics_discussion_ids.rb
new file mode 100644
index 00000000000..1a80ccdee92
--- /dev/null
+++ b/lib/gitlab/background_migration/fix_promoted_epics_discussion_ids.rb
@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module BackgroundMigration
+    # This migration updates discussion ids for epics that were promoted from issue so that the discussion id on epics
+    # is different from discussion id on issue, which was causing problems when replying to epic discussions as it would
+    # identify the discussion as related to an issue and complaint about missing project_id
+    class FixPromotedEpicsDiscussionIds
+      # notes model to iterate through the notes to be updated
+      class Note < ActiveRecord::Base
+        self.table_name = 'notes'
+        self.inheritance_column = :_type_disabled
+      end
+
+      def perform(discussion_ids)
+        Note.where(noteable_type: 'Epic')
+          .where(discussion_id: discussion_ids)
+          .update_all("discussion_id=MD5(discussion_id)||substring(discussion_id from 1 for 8)")
+      end
+    end
+  end
+end