jEasyUI tree grid lazy loading nodes

Sometimes we have obtained sufficient hierarchical tree grid (TreeGrid) data. We also want the TreeGrid to lazily load nodes hierarchically. First, only the top-level nodes are loaded. Then click the node's expand icon to load its child nodes. This tutorial shows how to create a TreeGrid with lazy loading.

Create a tree grid (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>

In order to place loaded child nodes, we need to rename the 'children' attribute for each node. As shown in the code below, the 'children' property is renamed to 'children1'. When a node is expanded, 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;
	}

Download jQuery EasyUI instance

jeasyui-tree-treegrid5.zip