What do I need to change in order to get this to work using ajax?

**doheja07** · 06-18-2009, 10:38 PM

I created a code. When I run the code using php, it is very inneficient. I figured I could significantly improve my UI if I could use ajax. The problem is, I am new to javascript and ajax. I have been following a tutorial to get a idea as to how I should write the code, but for some reason it doesn't work. It does work, however, when it is just php. Could somebody give me an idea as to what I need to change so that the code will work with ajax?

This is upload.php:

Code:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Untitled Document</title>
</head>
<?php
require_once("connection.php");
require_once("functions.php");
?>
<script type="text/javascript" src="getcategories.js"></script>

<body>
<form action="upload2.php" method="post">
<select name="categories" onchange="getSubcategories(this.value)">

<?php
get_selectable_categories();
?>
</select>
<select name="subcategories" onchange="getSubsubcategories(this.value)">
</select>
<select name="subsubcategories">
</select>
<input type="submit" name="submit" value="Submit" />
</form>
<?php
mysql_close($connection);
?>

</body>
</html>

This is getCategories.js:

Code:

window.onload = getCategories;

var xhr;

function getCategories() {
	xhr=GetXmlHttpObject();
if (xhr==null)
  {
  alert ("Browser does not support HTTP Request");
  return;
  }
var url = "categories.php";
url = url+"sid="+Math.random();
xhr.onreadystatechange=stateChanged;
xhr.open("GET",url,true);
xhr.send(null);
}

function getSubcategories(id) {
	xhr=GetXmlHttpObject();
if (xhr==null)
  {
  alert ("Browser does not support HTTP Request");
  return;
  }
var url = "subcategories.php";
var url = url+"?id="+id;
url = url+"sid="+Math.random();
xhr.onreadystatechange=stateChanged;
xhr.open("GET",url,true);
xhr.send(null);
}

function getSubsubcategories(id) {
	xhr=GetXmlHttpObject();
if (xhr==null)
  {
  alert ("Browser does not support HTTP Request");
  return;
  }
var url = "subsubcategories.php";
var url = url+"?id="+id;
url = url+"sid="+Math.random();
xhr.onreadystatechange=stateChanged;
xhr.open("GET",url,true);
xhr.send(null);
}

function stateChanged()
{
if (xhr.readyState==4)
{
document.getElementById("categories").innerHTML=xhr.responseText;
}
}

function GetXmlHttpObject()
{
if (window.XMLHttpRequest)
  {
  // code for IE7+, Firefox, Chrome, Opera, Safari
  return new XMLHttpRequest();
  }
if (window.ActiveXObject)
  {
  // code for IE6, IE5
  return new ActiveXObject("Microsoft.XMLHTTP");
  }
return null;
}

This is categories.php:

Code:

<?php require_once("connection.php"); ?>
<?php require_once("functions.php"); ?>
<?php get_selectable_categories(); ?>
<?php mysql_close($connection); ?>

This is subcategories.php:

Code:

<?php require_once("connection.php"); ?>
<?php require_once("functions.php"); ?>
<?php $id = $_GET['id']; ?>
<?php get_selectable_subcategories($id); ?>
<?php mysql_close($connection); ?>

This is subsubcategories.php:

Code:

<?php require_once("connection.php"); ?>
<?php require_once("functions.php"); ?>
<?php $id = $_GET['id']; ?>
<?php get_selectable_subsubcategories($id); ?>
<?php mysql_close($connection); ?>

This is functions.php:

Code:

<?php

function confirm_query($result_set) {
		if (!$result_set) {
			die("Database query failed: " . mysql_error());
		}
	}

function get_all_categories() {
		global $connection;
		$query = "SELECT *
				  FROM categories
				  WHERE visible = 1
				  ORDER BY cat_name ASC";
		$category_set = mysql_query($query, $connection);
		confirm_query($category_set);
		return $category_set;
	}
	
function get_selectable_categories() {	
	$categories = get_all_categories();
	while($category = mysql_fetch_assoc($categories)) {
		echo "<option value=" . $category['id'] . "";
		echo ">" . $category['cat_name']. "</option>";
	}
}

function get_subcategories_for_category($id) {
	global $connection;
	$query = "SELECT *
			  FROM subcategories
			  WHERE cat_id = $id
			  AND visible = 1
			  ORDER BY subcat_name ASC";
	$subcategory_set = mysql_query($query, $connection);
	confirm_query($subcategory_set);
	return $subcategory_set;
}

function get_selectable_subcategories($id) {	
	$subcategories = get_subcategories_for_category($id);
	while($subcategory = mysql_fetch_assoc($subcategories)) {
		echo "<option value=" . $subcategory['id'] . "";
		echo ">" . $subcategory['subcat_name']. "</option>";
	}
}

function get_subsubcategories_for_subcategory($id) {
	global $connection;
	$query = "SELECT *
			  FROM subsubcategories
			  WHERE subcat_id = $id
			  AND visible = 1
			  ORDER BY subsubcat_name ASC";
	$subsubcategory_set = mysql_query($query, $connection);
	confirm_query($subsubcategory_set);
	return $subsubcategory_set;
}

function get_selectable_subsubcategories($id) {	
	$subsubcategories = get_subsubcategories_for_subcategory($id);
	while($subsubcategory = mysql_fetch_assoc($subsubcategories)) {
		echo "<option value=" . $subsubcategory['id'] . "";
		echo ">" . $subsubcategory['subsubcat_name']. "</option>";
	}
}
	
?>

I would really appreciate it if somebody could tell me how to get the ajax version of this working.

**xsonline** · 08-08-2009, 05:59 PM

It looks fine by me. Only, in getCategories I see you have done this

Code:

xhr.onreadystatechange=stateChanged;

Try changing it in:

Code:

xhr.onreadystatechange=stateChanged();

Keep me posted

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