Datagrid 显示数据是最新的，但$('#datagrid').datagrid('getSelections')取得的选中数据不是最新的

项目中使用了easyui的datagrid和dialog,dialog中包括了一个datagrid.

<div id="dlg-role-edit" href="" modal="true"         style="width:500px;height:300px;padding:15px 10px" closed="true"        buttons="#dlg-buttons-user_roles"><input type="hidden" id="currentSelectUserId" name="currentSelectUserId" />?                <table id="dg-user-roles"></table></div><div id="dlg-buttons-user_roles"><a href="#" iconCls="icon-ok" onclick="saveUserRoles()">Save</a><a href="#" iconCls="icon-cancel" onclick="javascript:$('#dlg-role-edit').dialog('close')">Cancel</a></div>

?页面点击编辑按钮时，弹出这个dialog,并刷新datagrid "dg-user-roles'中的数据，点击dialog的save按钮时，保存数据。javascript 代码如下：

          function editRole() {    var row = $('#dg').datagrid('getSelected');if (row){document.getElementById("currentSelectUserId").value= row.userId;//alert(document.getElementById("currentSelectUserId").value);$('#dlg-role-edit').dialog('open')$('#dlg-role-edit').dialog('setTitle','Edit user\'s roles');$('#dg-user-roles').datagrid({    title:'Current user:' +row.userName,    iconCls:'',    url:'${ctx}/accountmanagement/user/listUserRoles.html?userId='+row.userId,    idField:'roleId',    height:200,    pagination:false,    fitColumns:true,    columns:[[        {field:'checked',checkbox:true},        {field:'roleName',title:'Role Name',width:200},        {field:'roleDesc',title:'Role Description',width:200}    ]],     onLoadSuccess:function() {    var rows = $('#dg-user-roles').datagrid('getRows')var rowcount = rows.length;for(var i=0; i<rowcount; i++){alert(rows[i].roleId);if(rows[i].checked) {$('#dg-user-roles').datagrid('selectRow',i);} else {$('#dg-user-roles').datagrid('unselectRow',i);}}    }    });} else {$.messager.alert('',"Please select one user to edit roles.");}    }        function saveUserRoles() {    var currentSelectUserId = document.getElementById("currentSelectUserId").value;    var selectedRows = $('#dg-user-roles').datagrid('getSelections');    alert(currentSelectUserId);    alert(selectedRows);    alert(selectedRows.length);    var rowcount = selectedRows.length;    var var_roleIds = "";    if(rowcount == 0) {    $.messager.alert('',"Please at least select a role for user.");    } else {    for(var i=0; i<rowcount; i++){    var_roleIds +=","+selectedRows[i].roleId;    }    if(var_roleIds != "" && var_roleIds.length != 0) {    var_roleIds = var_roleIds.substr(1);    }    alert("var_roleIds: " + var_roleIds);    $.post('${ctx}/accountmanagement/user/userEditRoles.html',{userId:currentSelectUserId,roleIds:var_roleIds},function(result){if (result.success){$.messager.alert('',result.msg);$('#dlg-role-edit').dialog('close', 'forceClose');} else {$.messager.alert('',result.msg);}},'json');    }    }

?使用上面的代码在再次打开dialog时显示的是新数据，但是通过$('#dg-user-roles').datagrid('getSelections')得到的却是上次点开时选中的的旧数据。为解决这个问题，将上面的js代码改为下面，重点是先取消所有选中，然后重新加载

var is_dg_user_roles_init = false;    function editRole() {    var row = $('#dg').datagrid('getSelected');if (row){document.getElementById("currentSelectUserId").value= row.userId;//alert(document.getElementById("currentSelectUserId").value);$('#dlg-role-edit').dialog('open')$('#dlg-role-edit').dialog('setTitle','Edit user\'s roles');if(!is_dg_user_roles_init) {alert("firsttime");$('#dg-user-roles').datagrid({    title:'Current user:' +row.userName,    iconCls:'',    url:'${ctx}/accountmanagement/user/listUserRoles.html?userId='+row.userId,    idField:'roleId',    height:200,    pagination:false,    fitColumns:true,    columns:[[        {field:'checked',checkbox:true},        {field:'roleName',title:'Role Name',width:200},        {field:'roleDesc',title:'Role Description',width:200}    ]],     onLoadSuccess:function() {    var rows = $('#dg-user-roles').datagrid('getRows')var rowcount = rows.length;for(var i=0; i<rowcount; i++){alert(rows[i].roleId);if(rows[i].checked) {$('#dg-user-roles').datagrid('selectRow',i);} else {$('#dg-user-roles').datagrid('unselectRow',i);}}    }    });    is_dg_user_roles_init = true;} else {alert("not firsttime");                                        $('#dg-user-roles').datagrid('clearSelections');                                       ?$('#dg-user-roles').datagrid('options').url = '${ctx}/accountmanagement/user/listUserRoles.html?userId='+row.userId;$('#dg-user-roles').datagrid('reload');}} else {$.messager.alert('',"Please select one user to edit roles.");}    }        function saveUserRoles() {    var currentSelectUserId = document.getElementById("currentSelectUserId").value;    var selectedRows = $('#dg-user-roles').datagrid('getSelections');    alert(currentSelectUserId);    alert(selectedRows);    alert(selectedRows.length);    var rowcount = selectedRows.length;    var var_roleIds = "";    if(rowcount == 0) {    $.messager.alert('',"Please at least select a role for user.");    } else {    for(var i=0; i<rowcount; i++){    var_roleIds +=","+selectedRows[i].roleId;    }    if(var_roleIds != "" && var_roleIds.length != 0) {    var_roleIds = var_roleIds.substr(1);    }    alert("var_roleIds: " + var_roleIds);    $.post('${ctx}/accountmanagement/user/userEditRoles.html',{userId:currentSelectUserId,roleIds:var_roleIds},function(result){if (result.success){$.messager.alert('',result.msg);$('#dlg-role-edit').dialog('close', 'forceClose');} else {$.messager.alert('',result.msg);}},'json');    }    }