ext初学者提问（EXT 4)


var selModel = Ext.create('Ext.selection.CheckboxModel');        Ext.create('Ext.grid.Panel', {
            title: '員工建檔',
            store: employeeStore,
            selModel: selModel,
            columnLines: true,
            columns: [
                Ext.create('Ext.grid.RowNumberer'),
              { header: '員工編號', dataIndex: 'EMPNO', width: 80 },
              { header: '姓名', dataIndex: 'FULLNAME', width: 120 },
              { header: '地址', dataIndex: 'ADDRESS', flex: 1 },
              { header: '年齡', dataIndex: 'AGE', width: 60 },
              { header: '薪水', dataIndex: 'SALARY' },
              { header: 'Email', dataIndex: 'EMAIL', renderer: function (value) { return Ext.String.format('<a href="mailto:{0}">{1}</a>', value, value); } },
              { header: '部門編號', dataIndex: 'DEPTNO', width: 60, renderer: function (value) {
                  return Ext.String.format('<a href="/HumanResource/Department/{0}">{1}</a>', value, value);
              }
              }
      ],
            dockedItems: [
            {
                dock: 'top',
                xtype: 'toolbar',
                items: [{
                    itemId: 'Button',
                    text: '刪除',
                    tooltip: '刪除用戶資料',
                    iconCls: 'delete',
                    handler: function () {
                        var record = grid.getSelectionModel().getSelection();
                        if (record.length == 0) {
                            Ext.MessageBox.show({
                                title: "提示",
                                msg: "请先选择您要操作的行!"
                                //icon: Ext.MessageBox.INFO 
                            })
                            return;
                        } else {
                            var ids = "";
                            for (var i = 0; i < record.length; i++) {
                                ids += record[i].get("id")
                                if (i < record.length - 1) {
                                    ids = ids + ",";
                                }
                            }
                            Ext.MessageBox.show({
                                title: "所选ID列表",
                                msg: ids
                                //icon: Ext.MessageBox.INFO 
                            })
                        }
                    }
                }]
            },
            {
                dock: 'bottom',
                xtype: 'pagingtoolbar',
                store: employeeStore,
                pageSize: 3,
                displayInfo: true,
                displayMsg: '顯示 {0} - {1} 條，共計 {2} 條',
                emptyMsg: '没有数据'
            }],            height: 400,
            width: 800,
            disableSelection: false,
            renderTo: 'grid'
        });
为什么一直出现 grid.getSelectionModel()没有定义。