default value with ajax on jqgrid - php

Question

I'm using phpGrid library based on jqgrid and I have this function:
onSelectRow: function(id){
var grid = $(this);
if(id && id!==lastSel){
grid.restoreRow(lastSel);
lastSel = id;
var rd = jQuery("#php_temp_det_vo").jqGrid("getCell", id, "status");
if(rd == 1){
alert("Data cannot be changed");
$("#'. $this->jq_gridName .'").trigger("reloadGrid");
}
else{
$(function(){ $("#begin_km").val("123"); });
}
}
grid.editRow(id, true,oneditfunc,"","","",aftersavefunc);
}
I need to dynamically give default value to one column called begin_km depends on some function that I will generate later. I wanted to try $(function(){ $("#begin_km").val("123"); }); first without that function I mentioned, but it doesn't work whereas it works on a simple html page:
the ajax
$(function(){ $("#aaa").val("123"); });
the html
<input type="text" id="aaa" />
What is the problem and how can I fix it?
EDITED:
Here's a slice of my jqgrid column model *refering to begin_id as column ID
<script type="text/javascript">
...
colModel:[{"name":"id","id":"id","index":"id","hidden":true},
{"name":"begin_km","id":"begin_km","index":"begin_km","hidden":false,"align":"right"},
...
</script>

Answer 1

You can set the cell values using setCell
onSelectRow: function(id){
var grid = $(this);
if(id && id!==lastSel){
grid.restoreRow(lastSel);
lastSel = id;
var rd = jQuery("#php_temp_det_vo").jqGrid("getCell", id, "status");
if(rd == 1){
alert("Data cannot be changed");
$("#'. $this->jq_gridName .'").trigger("reloadGrid");
}
else{
grid.jqGrid('setCell', id, 'begin_km', "123");
}
}
grid.editRow(id, true,oneditfunc,"","","",aftersavefunc);
}