jQuery EasyUI 树形菜单 - 树形网格惰性加载节点

有时我们已经得到充分的分层树形网格（TreeGrid）的数据。我们还想让树形网格（TreeGrid）按层次惰性加载节点。首先，只加载顶层节点。然后点击节点的展开图标来加载它的子节点。本教程展示如何创建带有惰性加载特性的树形网格（TreeGrid）。

创建树形网格（TreeGrid）

    <table id="test" title="Folder Browser" class="easyui-treegrid" style="width:700px;height:300px"
            data-options="
                url: 'data/treegrid_data.json',
                method: 'get',
                rownumbers: true,
                idField: 'id',
                treeField: 'name',
                loadFilter: myLoadFilter
            ">
        <thead>
            <tr>
                <th field="name" width="220">Name</th>
                <th field="size" width="100" align="right">Size</th>
                <th field="date" width="150">Modified Date</th>
            </tr>
        </thead>
    </table>

为了放置加载子节点，我们需要为每个节点重命名 'children' 属性。正如下面的代码所示，'children' 属性重命名为 'children1'。当展开一个节点时，我们调用 'append' 方法来加载它的子节点数据。

'loadFilter' 代码

    function myLoadFilter(data,parentId){
        function setData(){
            var todo = [];
            for(var i=0; i<data.length; i++){
                todo.push(data[i]);
            }
            while(todo.length){
                var node = todo.shift();
                if (node.children){
                    node.state = 'closed';
                    node.children1 = node.children;
                    node.children = undefined;
                    todo = todo.concat(node.children1);
                }
            }
        }
        
        setData(data);
        var tg = $(this);
        var opts = tg.treegrid('options');
        opts.onBeforeExpand = function(row){
            if (row.children1){
                tg.treegrid('append',{
                    parent: row[opts.idField],
                    data: row.children1
                });
                row.children1 = undefined;
                tg.treegrid('expand', row[opts.idField]);
            }
            return row.children1 == undefined;
        };
        return data;
    }