Add migration to set default values for contacts

db/migrate/20230512040636_set_default_name_to_existing_contacts.rb

@@ -0,0 +1,13 @@
+class SetDefaultNameToExistingContacts < ActiveRecord::Migration[7.0]
+  def change
+    Contact.where(name: nil).each do |contact|
+      contact.update(name: '')
+    end
+  end
+
+  def down
+    Contact.where(name: '').each do |contact|
+      contact.update(name: nil)
+    end
+  end
+end