EASYUI TREEGRID异步加载数据实现方法

官方提供的treegrid的ex 我给大家贴出来看看吧：

$(function(){ 
$('#tt').treegrid({ 
url:'treegrid_data3.json', 
onAfterEdit:function(row,changes){ 
alert(row.name); 
} 
}); 
}) 

这个是页面初始化的。
看看他的JSON:

复制代码代码如下:

{"total":117,"rows":[ 
<SPAN style="COLOR: #ff0000">{"id":1,"code":"code1","name":"name1","addr":"address1","state":"closed"},</SPAN> 
{"id":11,"code":"code11","name":"name11","addr":"address11","<SPAN style="COLOR: #ff0000">_parentId":1</SPAN>}, 
{"id":12,"code":"code12","name":"name12","addr":"address12","<SPAN style="COLOR: #ff0000">_parentId":1</SPAN>}, 
{"id":21,"code":"code21","name":"name21","addr":"address21","_parentId":1}, 
{"id":22,"code":"code22","name":"name22","addr":"address22","_parentId":1}, 
{"id":31,"code":"code31","name":"name31","addr":"address31","_parentId":1}, 
{"id":32,"code":"code32","name":"name32","addr":"address32","_parentId":1}, 
{"id":41,"code":"code41","name":"name41","addr":"address41","_parentId":1}, 
{"id":42,"code":"code42","name":"name42","addr":"address42","_parentId":1}, 
{"id":51,"code":"code51","name":"name51","addr":"address51","_parentId":1}, 
{"id":52,"code":"code52","name":"name52","addr":"address52","_parentId":1}, 
{"id":61,"code":"code61","name":"name61","addr":"address61","_parentId":1}, 
{"id":62,"code":"code62","name":"name62","addr":"address62","_parentId":1}, 
{"id":71,"code":"code71","name":"name71","addr":"address71","_parentId":1}, 
{"id":72,"code":"code72","name":"name72","addr":"address72","_parentId":1}, 
{"id":81,"code":"code81","name":"name81","addr":"address81","_parentId":1}, 
{"id":82,"code":"code82","name":"name82","addr":"address82","_parentId":1}, 
{"id":91,"code":"code91","name":"name91","addr":"address91","_parentId":1}, 
{"id":92,"code":"code92","name":"name92","addr":"address92","_parentId":1}, 
{"id":110,"code":"code110","name":"name110","addr":"address110","_parentId":1}, 
{"id":120,"code":"code120","name":"name120","addr":"address120","_parentId":1} 
]} 

标红的地方是特别有用的，我按照他的这个做法，自己做了一个，始终是没有数据的，后来发现了一个问题，

复制代码代码如下:

{"total":29,"rows":[ 
{"Id":25,"Ids":25,"name":"直辖市","state":"closed",<SPAN style="COLOR: #ff0000">"_parentId":2</SPAN>,"orderId":2}, 
{"Id":44,"Ids":44,"name":"黑龙江","state":"closed","_parentId":2,"orderId":110}, 
{"Id":45,"Ids":45,"name":"吉林","state":"closed","_parentId":2,"orderId":1}, 
{"Id":46,"Ids":46,"name":"辽宁","state":"closed","_parentId":2,"orderId":3}, 
{"Id":47,"Ids":47,"name":"河北","state":"closed","_parentId":2,"orderId":4}, 
{"Id":48,"Ids":48,"name":"内蒙古","state":"closed","_parentId":2,"orderId":111}, 
{"Id":49,"Ids":49,"name":"山西","state":"closed","_parentId":2,"orderId":6}, 
{"Id":50,"Ids":50,"name":"江西","state":"closed","_parentId":2,"orderId":11}, 
{"Id":51,"Ids":51,"name":"山东","state":"closed","_parentId":2,"orderId":12}, 
{"Id":52,"Ids":52,"name":"台湾","state":"closed","_parentId":2,"orderId":13}, 
{"Id":53,"Ids":53,"name":"甘肃","state":"closed","_parentId":2,"orderId":15}, 
{"Id":54,"Ids":54,"name":"宁夏","state":"closed","_parentId":2,"orderId":16}, 
{"Id":55,"Ids":55,"name":"青海","state":"closed","_parentId":2,"orderId":17}, 
{"Id":56,"Ids":56,"name":"新疆","state":"closed","_parentId":2,"orderId":18}, 
{"Id":57,"Ids":57,"name":"云南","state":"closed","_parentId":2,"orderId":19}]} 

上面这个数据没有一个根节点，所以页面出来什么都没有。。。。。我的数据只有parentId这个玩意，所以页面一片空白。
这个问题修正了，但是又出现新的问题了。开始我的处理方式是直接把所有数据load进来，点击节点展开是没有问题的。但是所有数据一起装载，不光耗性能不说，还特别慢。
所以想到异步加载。又到官方上去看了半天，官方提供了一大堆事件，什么展开触发哦之类的，没有一个说到点上的。
我用火狐监听每次数据都加载了的，而且有返回正确的JSON

复制代码代码如下:

{"total":29,"rows":[ 
{"Id":25,"Ids":25,"name":"直辖市","state":"closed",<SPAN style="COLOR: #ff0000">"_parentId":2</SPAN>,"orderId":2}, 
{"Id":44,"Ids":44,"name":"黑龙江","state":"closed","_parentId":2,"orderId":110}, 

。。。。<BR>经过我反复的对比tree和这个treegrid。最后发现treegrid 在请求过来的数据上有个total和rows ，而tree没有。

难道是这个total和rows在作怪，我赶紧把这个删掉了，果然数据出来了

大家可以百度一下，各种说法都有。

最后一个小结： easyui treegrid使用时需注意：

　　1、必须要有根节点;

2、父节点装载的数据格式和子节点装载的数据格式是不一样的。
父节点需要total和rows 而子节点装载的时候和tree的数据格式相同。目前只弄了个两级的，多级的还没有去试。留篇文章，以备后用。

也热烈欢迎大家指正。