jQuery EasyUI Tree Menu - TreeGrid Lazy Loading Nodes
Sometimes we have already obtained hierarchical TreeGrid data. We also want the TreeGrid to load nodes hierarchically lazily. First, only load the top-level nodes. Then click the expand icon of a node to load its child nodes. This tutorial shows how to create a TreeGrid with lazy loading features.
Create 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>
To prevent loading child nodes, we need to rename the 'children' attribute for each node. As shown in the following code, the 'children' attribute is renamed to 'children1'. When expanding a node, we call the 'append' method to load its child node data.
'loadFilter' Code
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;
}