easyui treegrid 控制节点展开等级

建议修改返回的json格式，不直接嵌套。而是采用父节点ID的方式。如：var treeData =[
{"id":"1200000100","parentId":"0","text":"苏州报表中心","staffId":"1200001016","level":"1","state":"closed"},
{"id":"1200000345","parentId":"1200000100","text":"周期报表","staffId":"1200001016","level":"2","state":"closed"},
{"id":"1200001245","parentId":"1200000100","text":"报表模板","staffId":"1200001016","level":"2","state":"closed"},
{"id":"1200001487","parentId":"1200000345","text":"创电中心","staffId":"1200001016","level":"3","state":"closed"},
{"id":"1200001540","parentId":"1200001245","text":"报表测"}]

根据前台根据parentId来生成tree.源码可参考我的博客：网页链接

我补充一下问题：其实我的问题是treegrid如何异步加载节点数据?就是第一次加载的时候只把第一层的节点展示出来，这些节点下面的二级子节点不查询出来，当用户点击某个节点的时候，才去查询数据库，显示这个节点下面的子节点。

你返回的json呢