i setting hidden field value using jquery this
select: function (event, ui) { $("#<%=hfpatientid.clientid %>").val(ui.item.val); } and want store value in 1 of property. in code behind did this.

objticketbo.patient_id = hfpatientid.value.tostring(); now problem selected value binding in right side of = not binding on left side. i.e on hovering on .value getting value. on running code throwing error nullvaluevalidation.
problem: code
select: function (event, ui) { $("#<%=hfpatientid.clientid %>").val(ui.item.val); } can't work, because try select asp element naming in jquery, final html elements.
solution: supposing asp produce element
<input type="hidden" name="clientid" id="clientid" value="225"> so jquery function seeking is
select: function (event, ui) { $("#clientid").val(ui.item.val); } if id of hidden element not clientid, change jquery selector accordingly.