Question

I’m trying to do a simple exercise querying a database from JS using XMLHTTPrequest Object and POST method. Basically I pass a string to PHP server, it recieves it, queries DB and returns an XML from where I read the information with JS, but something is not working: the callback function that should be executed after request is ready.

Here’s the JS code:

function leerDNI(dni){

var params="dni="+dni;

downloadUrl(params,"genxml.php", function(data) {
    var xml = parseXml(data);//THIS IS NOT BEING EXECUTED
    var dnis = xml.documentElement.getElementsByTagName("dni");//THIS IS NOT BEING EXECUTED
    for (var i = 0; i < dnis.length; i++) {//THIS IS NOT BEING EXECUTED
    var name = dnis[i].getAttribute("name");
    alert(name); //THIS IS NOT BEING EXECUTED
    document.getElementById("name").value=name; //THIS IS NOT BEING EXECUTED
 }
 });

 }

function downloadUrl(params,url, callback) {
 var request = window.ActiveXObject ?
 new ActiveXObject('Microsoft.XMLHTTP') :
 new XMLHttpRequest; 

request.onreadystatechange = function() {
 if (request.readyState == 4) {
 request.onreadystatechange = doNothing;
 callback(request.responseText, request.status);

 }
 };
 request.open("POST", url, true);
 request.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");//creación de headers
 request.send(params);//enviamos la petición POST
}

function parseXml(str) {
 if (window.ActiveXObject) {
 var doc = new ActiveXObject('Microsoft.XMLDOM');
 doc.loadXML(str);
 return doc;
 } else if (window.DOMParser) {
 return (new DOMParser).parseFromString(str, 'text/xml');
 }
}

function doNothing() {}  

The XML is being generated correctly. Anyone can light me up with what’s wrong in my code? Thank you very much!

Answer 1

I’ve solved the issue, it was this line:

var dnis = xml.documentElement.getElementsByTagName("dni");

That was supossed to be substituted for:

var dnis = xml.documentElement.getElementsByTagName("persona");

Because I was generating persona nodes.

Thanks for your answers!