How to reload JQuery grid keeping scroll position and collapse elements open

I'm currently working with JQuery plugin for struts2. I would like to know how to reload a JQuery grid without loosing the current scroll position and collapse rows.

In order to reload the data in the grid I'm using the following javascript code:

var timerID = setInterval("RefreshGridData()", 5000);
function RefreshGridData() {
    $("#griditems").trigger("reloadGrid");
}

The jsp of the grid is the following:

<s:url id="itemsurl" action="getItemsJson.action" />
<s:url id="subitemsurl" action="getSubItemsJson.action" />
<sjg:grid id="griditems" caption="Items and Subitems" dataType="json"
    href="%{itemsurl}" pager="false" viewrecords="true" height="400"
    gridModel="gridModel" rowNum="-1" sortable="true">

    <sjg:grid id="gridsubitems" subGridUrl="%{subitemsurl}"
        gridModel="gridModel" rowNum="-1">
        <sjg:gridColumn name="subcol1" index="subcol1" title="SubColumn 1"
            width="120" />
        <sjg:gridColumn name="subcol2" index="subcol2" title="SubColumn 2"
            align="left" width="120" />
    </sjg:grid>

    <sjg:gridColumn name=开发者_运维技巧"col1" index="col1" title="Column 1" sortable="true"
        width="80"/>
    <sjg:gridColumn name="col2" index="col2"
        title="Column 2" sortable="true" />
    <sjg:gridColumn name="col3" index="col3" title="Column 3"
        sortable="true" />
</sjg:grid>

Any comments on how to implement this are welcome.

Thanks in advance.

var scrollPosition = 0

function RefreshGridData() {
    scrollPosition = jQuery("#griditems").closest(".ui-jqgrid-bdiv").scrollTop()
    $("#griditems").trigger("reloadGrid");
}

after data is loaded in event loadComplete

jQuery("#griditems").closest(".ui-jqgrid-bdiv").scrollTop(scrollPosition)

EDIT :

var ids = new Array();


jQuery("#jqgrid_id").jqGrid({
...
   gridComplete: function(){ 
      var rowIds = $("#jqgrid_id").getDataIDs();
      $.each(ids, function (index, data) {
        if (data == 1){
           $("#jqgrid_id").expandSubGridRow(rowId); 
        }
      });
   },
   subGridRowExpanded: function(pID, id){ 
      ids[id] = 1;
   },
   subGridRowColapsed: function(pID, id){ 
      ids[id] = 0;
   },

...
});

not sure if this will work i didn't test it tut it should be something like that

EDIT

setGridParam - not suire if it will work on events but you might try that

i couldn't find how to attach subGridRowExpanded topick using tag library in struts but try changing config after grid is constructed by taglibrary

$("#griditems").setGridParam({subGridRowExpanded: function(pID, id){ ids[id] = 1;}});
$("#griditems").setGridParam({subGridRowColapsed: function(pID, id){ ids[id] = 0;}});
$("#griditems").setGridParam({gridComplete: function(){ 
      var rowIds = $("#jqgrid_id").getDataIDs();
      $.each(ids, function (index, data) {
        if (data == 1){
           $("#jqgrid_id").expandSubGridRow(rowId); 
        }
      });
   }});

EDIT

ok different aproach :

var scrollPosition = 0
var ids = new Array();

function RefreshGridData() {
        ids = new Array();
        $('tr:has(.sgexpanded)').each(function(){ids.push($(this).attr('id'))});
        scrollPosition = jQuery("#griditems").closest(".ui-jqgrid-bdiv").scrollTop()
        $("#griditems").trigger("reloadGrid");
    }

and when load of grid is complete :

jQuery.each(ids, function (id,data) {
           $("#jqgrid_id").expandSubGridRow(data);
           jQuery("#griditems").closest(".ui-jqgrid-bdiv").scrollTop(scrollPosition);
      });

I finally solved my problem. Thanks to the useful information provided by firegnom in his answer and comments I got a big push forward to create an implementation of a jQuery grid (with subgrid), using Struts2 tags, which keeps its previous scroll position and expanded/collapsed state after reloading it.

JavaScript

var scrollPosition = 0;
    var ids;
    var timerID = setInterval("RefreshGridData()", 5000);



function RefreshGridData() {
    var num;
    ids = new Array();  
    scrollPosition = jQuery("#testgrid").closest(".ui-jqgrid-bdiv").scrollTop();            
    jQuery("#testgrid tr:has(.sgexpanded)").each(function(){
        num = $(this).attr('id');
        if (isDigit(num)) {         
            ids.push(num);
        }
    }); 
    $("#testgrid").trigger("reloadGrid");           
}               

function isDigit(num) {         
    if (num.length > 1){return false;}                                  
    if (num > 0 && num < 20) {return true;}     
    return false;
}


$(document).ready(function () {         
$.subscribe('testgridReloded', function(event, element) {   
    var i;
    for (i = 0; i < ids.length; i = i+1) {                  
        $("#testgrid").jqGrid('expandSubGridRow', ids[i]);
    }    



    var t = setTimeout("setScrollPos()", 300);
    });
}); 



function setScrollPos() {
    jQuery("#testgrid").closest(".ui-jqgrid-bdiv").scrollTop(scrollPosition);
}

I used the isDigit function because the first element found with class sgexpanded is always 0 and that is not a valid row number in a grid since rows start counting from 1. Another observation is that I set a timer before calling the setScrollPos function because my grid doesn't have a scroll bar before a certain number of rows are expanded, and since the expanding effect is not immediate, it's necessary to set the scroll position after a certain time.

Grid tags code

<s:url id="gridurl" action="getJsonGridData.action" />

<sjg:grid id="testsubgrid" subGridUrl="%{subgridurl}"
    gridModel="gridModel" rowNum="-1" >
    <sjg:gridColumn name="sub1" index="sub1" title="Sub Col 1"
        width="80" />
    <sjg:gridColumn name="sub2" index="sub2" title="Sub Col 2"
        align="left" width="80" />
</sjg:grid>

<sjg:gridColumn name="col1" index="col1" title="Grid Col 1" sortable="true" width="120" />
<sjg:gridColumn name="col2" index="col2" title="Grid Col 2" width="120" />
<sjg:gridColumn name="col3" index="col3" title="Grid Col 3 width="120" />
</sjg:grid>

Hope it helps somebody.

Cheers.

To load the page in-place (which keeps curent scroll position) simply use:

$("#mygrid").trigger("reloadGrid",[{current:true}]);

I've solve the problem by adding this

var offset = $("#" + *subgrid_table_id*).offset();
var w = $(window);
var fromTop = offset.top - w.scrollTop();
$('html, body').animate({
    scrollTop: offset.top - fromTop
}, 1);

this code keep the last position of grid