工作的原因，以后主要做一些JavaWeb的开发工作，开辟这个文章集主要用来记录学习的过程和分享遇到的问题，方便日后回顾或许还能帮助网友解决相同的问题。

easyUi的TreeGrid的问题

easyui是个不错的前端库，以后好好学习学习。最近在做业务遇到了TreeGrid的加载问题。官方的手册的加载数据有三种是：

No.1：

[{
    "id":1,
    "name":"C",
    "size":"",
    "date":"02/19/2010",
    "children":[{
        "id":2,
        "name":"Program Files",
        "size":"120 MB",
        "date":"03/20/2010",
        "children":[{
            "id":21,
            "name":"Java",
            "size":"",
            "date":"01/13/2010",
            "state":"closed",
            "children":[{
                "id":211,
                "name":"java.exe",
                "size":"142 KB",
                "date":"01/13/2010"
            },{
                "id":212,
                "name":"jawt.dll",
                "size":"5 KB",
                "date":"01/13/2010"
            }]
        },{
            "id":22,
            "name":"MySQL",
            "size":"",
            "date":"01/13/2010",
            "state":"closed",
            "children":[{
                "id":221,
                "name":"my.ini",
                "size":"10 KB",
                "date":"02/26/2009"
            },{
                "id":222,
                "name":"my-huge.ini",
                "size":"5 KB",
                "date":"02/26/2009"
            },{
                "id":223,
                "name":"my-large.ini",
                "size":"5 KB",
                "date":"02/26/2009"
            }]
        }]
    },{
        "id":3,
        "name":"eclipse",
        "size":"",
        "date":"01/20/2010",
        "children":[{
            "id":31,
            "name":"eclipse.exe",
            "size":"56 KB",
            "date":"05/19/2009"
        },{
            "id":32,
            "name":"eclipse.ini",
            "size":"1 KB",
            "date":"04/20/2010"
        },{
            "id":33,
            "name":"notice.html",
            "size":"7 KB",
            "date":"03/17/2005"
        }]
    }]
}]

如上第一种是采用json嵌套的形式加载全部数据，这样很好理解，但是数据格式复杂，后台也不好返回这种数据。关键词 Children

No.2

{"total":7,"rows":[
    {"id":1,"name":"All Tasks","begin":"3/4/2010","end":"3/20/2010","progress":60,"iconCls":"icon-ok"},
    {"id":2,"name":"Designing","begin":"3/4/2010","end":"3/10/2010","progress":100,"_parentId":1,"state":"closed"},
    {"id":21,"name":"Database","persons":2,"begin":"3/4/2010","end":"3/6/2010","progress":100,"_parentId":2},
    {"id":22,"name":"UML","persons":1,"begin":"3/7/2010","end":"3/8/2010","progress":100,"_parentId":2},
    {"id":23,"name":"Export Document","persons":1,"begin":"3/9/2010","end":"3/10/2010","progress":100,"_parentId":2},
    {"id":3,"name":"Coding","persons":2,"begin":"3/11/2010","end":"3/18/2010","progress":80},
    {"id":4,"name":"Testing","persons":1,"begin":"3/19/2010","end":"3/20/2010","progress":20}
],"footer":[
    {"name":"Total Persons:","persons":7,"iconCls":"icon-sum"}
]}

第二种的Json数据没有嵌套关系，使用_parentId 来指定父节点。数据平行，可以直接从数据库中拿数据。且_parentId关键词被指定，不能改。
** ！！！着重看第一行，也就是根节点，并没有** _parentId ** ，有时根节点指定了该属性等于某值，如 ** _parentId=0 ，前端treegrid为空白，但是数据库中不可取消该属性，所以可以将根节点 _parentId=null， 即可，但是用html+js测试却没有该问题。自己看着办吧。
该类数据除了没有嵌套外，比第一种还多了 row和total和footer，不可去掉，否则也无法显示。后台返回数据时再封装一层吧。

No.3

[
    {"id":1,"name":"All Tasks","begin":"3/4/2010","end":"3/20/2010","progress":60,"iconCls":"icon-ok",state":"closed"},
    {"id":2,"name":"Designing","begin":"3/4/2010","end":"3/10/2010","progress":100,"state":"closed"},
    {"id":21,"name":"Database","persons":2,"begin":"3/4/2010","end":"3/6/2010","progress":100,state":"closed"},
    {"id":22,"name":"UML","persons":1,"begin":"3/7/2010","end":"3/8/2010","progress":100,state":"closed"},
    {"id":23,"name":"Export Document","persons":1,"begin":"3/9/2010","end":"3/10/2010","progress":100,"state":"closed"},
    {"id":3,"name":"Coding","persons":2,"begin":"3/11/2010","end":"3/18/2010","progress":80,"state":"closed"},
    {"id":4,"name":"Testing","persons":1,"begin":"3/19/2010","end":"3/20/2010","progress":20,"state":"closed"}
]

第三种，其实就是没有Childer和_parentId关键词，这样会有问题，怎么表示子父关系呢，对了，所以这中格式一般作为异步加载，即一次请求数据加载一层，就是把该层的id作为请求参数去后台拿数据，后台返回的就是该id的子节点，返回的数据时平级的，所以不用表示层级关系，一般在点击展开“+”时。有个关键词"state":"closed"，否则看到返回的数据有"state":"open"，会自动触发再去请求下一层。就达不到异步加载，就是点击展开就加载，这样可以避免一次全部数据性能跟不上，造成卡顿。

关于 .treeGrid('laod',{param:"value"})

在做后台的树结构查询时，用该函数带入表单的数据时，以后每次向后台取数据时，如点击展开的“+”按钮时，请求都会带进这个参数，因为easyUI会把该参数给记录。
看jquery.easyui.min.js源码：

function _670(_753,_754,cb){
var opts=$.data(_753,"datagrid").options;
if(_754){
opts.queryParams=_754;
}

其中，_754就是该参数，储存在options.queryParams属性中，以后的请求数据都会和作为post请求参数。
点击“+”展开时，又是一次查询函数的调用，导致无法展开。在查询函数里，最后添加：

$(#'xxxxx_treeGrid').treegrid('options').queryParams = null;

将该属性重置下。