Adding Bookmarks The Ajax Way

[rick.emmet]

Hi Everyone,

I took a PHP class that used PHP And MySQL Web Development by Welling and Thomson as our textbook and we were able to get through most of the book. We didn't have time to cover chapter 34 Building Web 2.0 Applications with AJAX though. I need to do some AJAX development and have proceeded to work with the examples in the book. The section, Adding Bookmarks the AJAX Way, has us changing a number of scripts that were used previously to make the interface more user friendly. I typed out the scripts and couldn't get them to run. I cut and pasted the code into my PHP pages and it still won't run, so I need a little help.

 

I found several typos which I corrected but the scripts will not run; the weird thing is that nothing happens when I click on the “Add bookmark” button. A new snippet of code has been added as a button attribute that invokes a javascript function which calls a PHP script to insert the bookmark into the database. These scripts have numerous error messages (exceptions), but not a single one is displayed on the page. I have a form which allows me to add a bookmark and there is a button to click on; and when I fill out the form and click on the button, the page does not change at all.

 

Since this is new to me, I'm having a hard time figuring out where the problem is. The PHP script requires both a bookmark and a valid user (both are input into the database). It looks as if the javascript function is only sending the bookmark, but since we really don't really leave the page, perhaps the PHP script can grab the valid user to process. I do want to learn this stuff (wish we had time to cover this in class!) and any advice would be most appreciated!

 

Here are the scripts:

THE AJAX.JS FILE

function getXMLHTTPRequest() {
var req = false;
try {
 /* for Firefox */
 req = new XMLHttpRequest();
} catch (err) {
 try {
	 /* for some versions of IE */
	 req = new ActiveXObject("Msxml2.XMLHTTP");
 } catch (err) {
	 try {
	 /* for some other versions of IE */
	 req = new ActiveXObject("Microsoft.XMLHTTP");
	 } catch (err) {
	 req = false;
	 }
 }
}

return req;
}

function addNewBookmark() {
var url = "add_bms.php";
var params = "new_url=" + encodeURI(document.getElementById('new_url').value);
myReq.open("POST", url, true);
myReq.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
myReq.setRequestHeader("Content-length", params.length);
myReq.setRequestHeader("Connection", "close");
myReq.onreadystatechange = addBMResponse;
myReq.send(params);
}

function addBMResponse() {
if (myReq.readyState == 4) {
if(myReq.status == 200) {
 result = myReq.responseText;
 document.getElementById('displayresult').innerHTML = result;
} else {
 alert('There was a problem with the request.');
}
}
}

 

THE ADD BOOKMARKS FUNCTION FROM THE OUTPUT LIBRARY

function display_add_bm_form() {
// display the form for people to enter a new bookmark in
?>
<script type="text/javascript">
var myReq = getXMLHTTPRequest();
</script>
<form>
<table width="250" cellpadding="2" cellspacing="0" bgcolor="#cccccc">
<tr><td>New BM:</td>
<td><input type="text" id="new_url" name="new_url" value="http://"
size="30" maxlength="255"/></td></tr>
<tr><td colspan="2" align="center">
<input type="button" value="Add bookmark"
onclick=" javascript:addNewBookmark();"/></td></tr>
</table>
</form>
<div id="displayresult"></div>
<?php
}

 

THE ADDBOOKMARKS PHP SCRIPT

<?php
require_once('bookmark_fns.php');
session_start();

//create short variable name
$new_url = $_POST['new_url'];

//check that form has been completed
if (!filled_out($_POST)) {
//has not
echo "<p class=\"warn\">Form not completely filled out.</p>";
} else {
// has; check and fix URL format if necessary
if (strstr($new_url, 'http://') === false) {
$new_url = 'http://'.$new_url;
}

// continue on to check URL is valid
if (!(@fopen($new_url, 'r'))) {
echo "<p class=\"warn\">Not a valid URL.</p>";
} else {
//it is valid, so continue to add it
add_bm($new_url);
}
}
// regardless of the status of the current request
// get the bookmarks this user has already saved
if ($url_array = get_user_urls($_SESSION['valid_user'])) {
display_user_urls($url_array);
}
?>

 

THE ADD_BM FUNCTION FROM THE URL FUNCTION LIBRARY

function add_bm($new_url) {
// Add new bookmark to the database

echo "Attempting to add ".htmlspecialchars($new_url)."<br />";
$valid_user = $_SESSION['valid_user'];

$conn = db_connect();

// check not a repeat bookmark
$result = $conn->query("select * from bookmark
where username='$valid_user'
and bm_URL='".$new_url."'");

if ($result && ($result->num_rows>0)) {
echo "<p class=\"warn\">Bookmark already exists.</p>";
} else {
//attempt to add
if (!$conn->query("insert into bookmark values
('".$valid_user."', '".$new_url."')")) {
echo "<p class=\"warn\">Bookmark could not be inserted.</p>";
} else {
echo "<p>Bookmark added.</p>";
}
}

return true;
}

 

THE DB_CONNECT FUNCTION FROM THE DB FUNCTION LIBRARYf

unction db_connect() {
$result = new mysqli('localhost', 'bm_user', 'password', 'bookmarks');
if (!$result) {
throw new Exception('Could not connect to database server');
} else {
return $result;
}
}

 

Looks all looks good to me, but I just started studying this so...

Thanks in advance for your help,

Rick