preserve submitter preferences

db/migrate/20231122203347_add_preferences_to_submissions.rb

@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+class AddPreferencesToSubmissions < ActiveRecord::Migration[7.0]
+  class MigrationSubmission < ApplicationRecord
+    self.table_name = 'submissions'
+  end
+
+  def change
+    add_column :submissions, :preferences, :text
+
+    MigrationSubmission.where(preferences: nil).update_all(preferences: '{}')
+
+    change_column_null :submissions, :preferences, false
+  end
+end