数据库模板字段变量赋值问题

.action{$tags := list }
.action{$blocks := queryBlocks "select DISTINCT * from blocks where root_id in (select root_id from blocks where id='?')" .id}
.action{ if not (empty $blocks) }
   .action{ $blockslen := ($blocks | len) }
   -- .action{ $blockslen } --
   .action{ range $v := $blocks }
     .action{ if not (empty $v.Tag) }
       == .action{ $tags } ==
       .action{$subTags := (splitList " " $v.Tag) }
       .action{$tags := (concat $tags $subTags) }
       -- .action{ $tags } --
     .action{ end }
   .action{ end }
   .action{ if not (empty $tags) }
       .action{ $tags }
   .action{ else }
   无
   .action{ end }
.action{ else }
无
.action{ end }

== .action{ $tags } == 为什么始终输出的空数组？