problem with ajax

amit1me · January 15th, 2007, 02:59 AM

hi everyone,
i am new to ajax, just was trying a few things
the first time i send a request to the web page i dont get any response ,and for every request send from the same page the server gets the same values that i send the first time ,the values dont change after that
what could be the possible reason for this

regards

surendran · January 16th, 2007, 01:07 AM

hi amit,
try this

HTML
<html>
<head>
<script src="selectcustomer.js"></script>
</head><body><form>
Select a Customer:
<select name="customers" onchange="showCustomer(this.value)">
<option value="ALFKI">Alfreds Futterkiste
<option value="NORTS ">North/South
<option value="WOLZA">Wolski Zajazd
</select>
</form><p>
<div id="txtHint"><b>Customer info will be listed here.</b></div>
</p></body>
</html> JavaScriptvar xmlHttp

function showCustomer(str)
{
xmlHttp=GetXmlHttpObject()
if (xmlHttp==null)
{
alert ("Browser does not support HTTP Request")
return
}
var url="getcustomer.asp"
url=url+"?q="+str
url=url+"&sid="+Math.random()
xmlHttp.onreadystatechange=stateChanged
xmlHttp.open("GET",url,true)
xmlHttp.send(null)
}

function stateChanged()
{
if (xmlHttp.readyState==4 || xmlHttp.readyState=="complete")
{
document.getElementById("txtHint").innerHTML=xmlHt tp.responseText
}
}

function GetXmlHttpObject()
{
var objXMLHttp=null
if (window.XMLHttpRequest)
{
objXMLHttp=new XMLHttpRequest()
}
else if (window.ActiveXObject)
{
objXMLHttp=new ActiveXObject("Microsoft.XMLHTTP")
}
return objXMLHttp
} Server sidesql="SELECT * FROM CUSTOMERS WHERE CUSTOMERID="
sql=sql & request.querystring("q")

set conn=Server.CreateObject("ADODB.Connection")
conn.Provider="Microsoft.Jet.OLEDB.4.0"
conn.Open(Server.Mappath("/db/northwind.mdb"))
set rs = Server.CreateObject("ADODB.recordset")
rs.Open sql, conn

response.write("<table>")
do until rs.EOF
for each x in rs.Fields
response.write("<tr><td><b>" & x.name & "</b></td>")
response.write("<td>" & x.value & "</td></tr>")
next
rs.MoveNext
loop

response.write("</table>")

surendran
(Anything is Possible)
http://ssuren.spaces.msn.com

amit1me · January 16th, 2007, 02:36 AM

hi surendran ,thank you for the reply
some how i got the think working ,but now i have another query

it is about xmlHttp.onreadystatechange

when i use this implementation the statechange is called only once
        try
        {
        var url = "muster_ajax.php"
        var params = "user="+username+"&password="+password+"&case=Logi n";

            alert(url+"=="+params);
        xmlHttp.open("POST",url,true);
        xmlHttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
         xmlHttp.setRequestHeader("Content-length", params.length);
         xmlHttp.setRequestHeader("Connection", "close");
        //alert("before state change");
        xmlHttp.onreadystatechange = StateChanged();
        alert("after ready state changed");
             xmlHttp.send(params);
        }
        catch(err)
        {
            alert(err.name + "error_message"+ err.message);
        }

here is my StateChanged Function
function StateChanged()
{
    if (xmlHttp.readyState == 4)
    {
        if (xmlHttp.status == 200 || xmlHttp.status == 304)
        {
            alert("here");
            alert(xmlHttp.responseText);
            //return xmlHttp.responseText;
        }
    }
    else if (xmlHttp.readyState == 0 )
    {
        alert("no result");
    }
    else
    {
        alert(xmlHttp.readyState+"loading");
    }
}

this way the StateChanges is called only once

And when i use implementation 2
ie

try
        {
        var url = "muster_ajax.php"
        var params = "user="+username+"&password="+password+"&case=Logi n";

            alert(url+"=="+params);
        xmlHttp.open("POST",url,true);
        xmlHttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
         xmlHttp.setRequestHeader("Content-length", params.length);
         xmlHttp.setRequestHeader("Connection", "close");
        //alert("before state change");
        xmlHttp.onreadystatechange = function ()
{
    if (xmlHttp.readyState == 4)
    {
        if (xmlHttp.status == 200 || xmlHttp.status == 304)
        {
            alert("here");
            alert(xmlHttp.responseText);
            //return xmlHttp.responseText;
        }
    }
    else if (xmlHttp.readyState == 0 )
    {
        alert("no result");
    }
    else
    {
        alert(xmlHttp.readyState+"loading");
    }
};

        alert("after ready state changed");
             xmlHttp.send(params);
        }
        catch(err)
        {
            alert(err.name + "error_message"+ err.message);
        }

the thing works fine

what could be the reason for such behaiour