EXTJS前台请求数据，后台有返回，但是load方法加载不出数据，且store中数据为空,求助

Question

var btnSearch = Ext.create('Ext.Button', {
                    text: '查询',
                    id: 'btnSearch',
                    iconCls: 'unknown-button', style: 'border:solid 1px gray;height:30px;width:60px;',
                    textAlign: 'center',
                handler: function () {
                    treeStore1.clearData();
                    var SNNo = Ext.getCmp("SNNo").value;
                    var MaterialBatch = Ext.getCmp("MaterialBatch").value;
                    var ProductionBillNo = Ext.getCmp("ProductionBillNo").value;
                    var TransferCard = Ext.getCmp("TransferCard").value;
                    var $url = 'Tracing.ashx?action=QueryRoot';
                    var $params = { snno: SNNo, materialbatch: MaterialBatch, productbillno: ProductionBillNo, transfercard: TransferCard };
                    //treeStore1.proxy.params = $params;
                    treeStore1.load({ params: $params });

                }  
            });

var treeStore1 = Ext.create('Ext.data.TreeStore', {
id: 'treestore1',
pageSize: 50,
autoLoad: false,
proxy: {
type: 'ajax',
url: 'Tracing.ashx?action=QueryRoot',
async: false,
}

        });

        var Billtree = Ext.create('Ext.tree.Panel', {
                id: 'Billtree',
                title: "生产流程信息",
                textAlign: 'center',
                collapsible: false,
                rootVisible: false,//是否显示根节点
                leaf:false,
                displayField: 'value',
                valueField: 'uid',
                store: treeStore1,
                listeners: {
                    itemclick: function () { 
                    }
                },
                columns: [
                    {
                        xtype: 'treecolumn',
                        header: '生产用料信息',
                        dataIndex: 'value',
                        sortable: false,
                        width:480
                    }
            ]
            });

Answer 1

检查下数据格式 包括json结构是否正确