up

# File activestorage/db/update_migrate/20180723000244_add_foreign_key_constraint_to_active_storage_attachments_for_blob_id.rb, line 2
  def up
    return if foreign_key_exists?(:active_storage_attachments, column: :blob_id)

    if table_exists?(:active_storage_blobs)
      add_foreign_key :active_storage_attachments, :active_storage_blobs, column: :blob_id
    end
  end