如何在jqGrid中隐藏和显示自定义按钮通过使用"reccount”;

我正试图在jqGrid上实现一个具有隐藏和显示功能的自定义按钮。我基本上想显示按钮，如果网格是空的，否则显示。

我已经用jqGrid中的"reccount"方法实现了它，以测试网格是否为空。但是我不确定我做得对不对。

代码末尾是我声明reccount的地方。请参阅"var计数"。

提前谢谢。

$("#sessioninfoGrid"+row_id).jqGrid({
    url:'/starburst/sessioninfoes/jsonlistbylectureoutline/'+row_id,
    datatype: "json",
    colNames: ['Session No.','Date','Start Time','End Time','Duration/Hours','Session Type','Topic','Room'],
    colModel: [
        {name:'sessionNumber',index:'SessionNumber', width:40, formoptions:{elmprefix:'(*) '}, editrules:{required:true}, editable:true, edittype: 'text'},
        {name:'sessionDate',index:'sessionDate', width:100, formoptions:{elmprefix:'(*) '}, editrules:{required:true}, editable:true, edittype: 'text',               
            editoptions: {
                dataInit: function(element) {
                    $(element).datepicker({dateFormat: 'DD, MM dd, yy'})
                }
            } 
        },
        {name:'starttime',index:'starttime', width:50, formoptions:{elmprefix:'(*) '}, editrules:{required:true}, editable:true, edittype: 'text'
        },
        {name:'endtime',index:'endtime', width:50, formoptions:{elmprefix:'(*) '}, editrules:{required:true}, editable:true, edittype: 'text'
        },
        {name:'durationPerSession',index:'durationPerSession', width:50, formoptions:{elmprefix:'(*) '}, editrules:{required:true}, editable:true, edittype: 'text'
        },
        {name:'sessionType',index:'sessionType', width:50, formoptions:{elmprefix:'(*) '}, editable:true, editrules:{required:true}, edittype: 'select',
            editoptions:{value:{}}
        },
        {name:'topic',index:'topic', width:200, formoptions:{elmprefix:'(*) '}, editable:true, editrules:{required:true}, edittype: 'text',
            editoptions: {
                dataInit: function(element) {
                    $(element).width(300)
                }
            }
        },
        {name:'room',index:'room', width:35}
    ],
    rowNum:10,
    autowidth: true,
    pager: sessioninfoPager_id,
    sortname: 'id', 
    viewrecords: true, 
    sortorder: "desc",
    editurl: '<c:url value="/sessioninfoes/update"/>',
    caption:"Session Info",
    emptyrecords: "Empty Records"                           
});
$("#sessioninfoGrid"+row_id).jqGrid('navGrid',"#"+sessioninfoPager_id,{edit:false,add:false,del:false,search:true},{ },{ },{ },
{ 
    sopt:['eq', 'ne', 'lt', 'gt', 'cn', 'bw', 'ew'],
    closeOnEscape: true, 
    multipleSearch: true, 
    closeAfterSearch: true 
}
);
$("#sessioninfoGrid"+row_id).navButtonAdd("#"+sessioninfoPager_id,
{   
    caption:"Add", 
    buttonicon:"ui-icon-plus", 
    onClickButton: addSessionInfoRow,
    position: "last", 
    title:"Add New Session Info", 
    cursor: "pointer"
} 
); 
$("#sessioninfoGrid"+row_id).navButtonAdd("#"+sessioninfoPager_id,
{   
    caption:"Edit", 
    buttonicon:"ui-icon-pencil", 
    onClickButton: editSessionInfoRow,
    position: "last", 
    title:"Edit Session Info", 
    cursor: "pointer"
} 
);
var count= $("#sessioninfoGrid"+row_id).jqGrid('getGridParam','reccount');
if (count == 0){
    $("#sessioninfoGrid"+row_id).navButtonAdd("#"+sessioninfoPager_id,
        {   
            caption:"Load Sessions",
            buttonicon:"ui-icon-plusthick", 
            onClickButton: function(){                                   
                $.post('<c:url value="/sessioninfoes/autocreate/"/>'+row_id,function(data){
                    $("#sessioninfoGrid"+row_id).trigger("reloadGrid");
                });                                  
            },
            position: "last", 
            title:"Load Session Infos", 
            cursor: "pointer"
        } 
    );
}