- required_uuids = Link.where(owner_uuid: system_user_uuid,
- link_class: 'signature',
- name: 'require',
- tail_uuid: system_user_uuid,
- head_kind: 'arvados#collection').
+ required_uuids = Link.where("owner_uuid = ? and link_class = ? and name = ? and tail_uuid = ? and head_uuid like ?",
+ system_user_uuid,
+ 'signature',
+ 'require',
+ system_user_uuid,
+ Collection.uuid_like_pattern).