Page 4 - Using Click Interceptions with a Database-Driven Application

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Using Click Interceptions with a Database-Driven Application

One of the most popular approaches used for extending the behavior of database-driven web applications is one widely known as click interception. In case you’ve not heard about it yet, this useful technique consists of using JavaScript to change the default behavior of an element included in a web page when a user clicks on it. This technique expands the element's functionality; it is covered in detail in this four-part series. This article is the third part.

Author Info:

By: Alejandro Gervasio

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November 19, 2008

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Using Click Interceptions with a Database-Driven Application - The full source code of the improved MySQL-driven application
(Page 4 of 4 )

As I promised you in the section that you just read, here are all of the source files that compose this basic MySQL-driven application after the behavior of the user detail web pages has been enriched by means of the click-interception approach:

(definition of 'list_users.htm' file)

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">

<head>

<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />

<title>Building with AJAX an user detail page using click interceptions</title>

<style type="text/css">

body{

padding: 0;

margin: 0;

background: #fff;

}

h1{

font: bold 18pt Arial, Helvetica, sans-serif;

color: #000;

}

h2{

font: bold 16pt Arial, Helvetica, sans-serif;

color: #000;

}

a:link,a:visited{

font: normal 10pt Arial, Helvetica, sans-serif;

color: #00f;

}

a:hover{

color: #f90;

}

p{

font: normal 10pt Arial, Helvetica, sans-serif;

color: #000;

}

#linkcontainer{

width: 300px;

padding: 5px;

background: #ffc;

}

#userviewer{

width: 300px;

}

</style>

<script language="javascript" type="text/javascript">

// send http requests

function sendHttpRequest(url,callbackFunc,respXml){

var xmlobj=null;

try{

xmlobj=new XMLHttpRequest();

}

catch(e){

try{

xmlobj=new ActiveXObject("Microsoft.XMLHTTP");

}

catch(e){

alert('AJAX is not supported by your browser!');

return false;

}

}

xmlobj.onreadystatechange=function(){

if(xmlobj.readyState==4){

if(xmlobj.status==200){

respXml?eval(callbackFunc+'(xmlobj.responseXML)'):eval(callbackFunc+'(xmlobj.responseText)');

}

}

}

// open socket connection

xmlobj.open('GET',url,true);

// send http header

xmlobj.setRequestHeader('Content-Type','text/html; charset=UTF-8');

// send http request

xmlobj.send(null);

}

// define 'displayUserDetails()' function

function displayUserDetails(userData){

var userviewer=document.getElementById('userviewer');

if(!userviewer){return};

userviewer.innerHTML=userData;

}

// define 'initializeLinks()' function

function initializeLinks(){

var lnkcont=document.getElementById('linkcontainer');

if(!lnkcont){return};

var links=lnkcont.getElementsByTagName('a');

if(!links){return};

for(var i=0;i<links.length;i++){

// use click interception to display user details on the same web page

links[i].onclick=function(){

sendHttpRequest('viewuserdetails.php?id='+this.href.split('=')[1],'displayUserDetails');

return false;

}

}

}

// call 'initializeLinks()' function when web page is loaded

window.onload=function(){

if(document.getElementById&&document.
getElementsByTagName&&document.createElement){

initializeLinks();

}

}

</script>

</head>

<body>

<h1>Example on building with AJAX an user detail page using click interception</h1>

<div id="linkcontainer">

<ul>

<li><a href="viewuserdetails.php?id=1" title="View details about Alejandro Gervasio...">View details about Alejandro Gervasio...</a></li>

<li><a href="viewuserdetails.php?id=2" title="View details about John Doe...">View details about John Doe...</a></li>

<li><a href="viewuserdetails.php?id=3" title="View details about Susan Norton...">View details about Susan Norton...</a></li>

<li><a href="viewuserdetails.php?id=4" title="View details about Marian Wilson...">View details about Marian Wilson...</a></li>

</ul>

</div>

<div id="userviewer"></div>

</body>

</html>

(definition of 'viewuserdetails.php' file)

<?php

// include classes

class MySQL{

private $host;

private $user;

private $password;

private $database;

private $conId;

// constructor

function __construct($options=array()){

if(!is_array($options)){

throw new Exception('Connection options must be an array');

}

foreach($options as $option=>$value){

if(empty($option)){

throw new Exception('Connection parameter cannot be empty');

}

$this->{$option}=$value;

}

$this->connectDb();

}

// private 'connectDb()' method

private function connectDb(){

if(!$this->conId=mysql_connect($this->host,$this->user,$this->password)){

throw new Exception('Error connecting to MySQL');

}

if(!mysql_select_db($this->database,$this->conId)){

throw new Exception('Error selecting database');

}

}

// public 'query()' method

public function query($sql){

if(!$result=mysql_query($sql)){

throw new Exception('Error running query '.$sql.' '.mysql_error());

}

return new Result($this,$result);

}

}

class Result{

private $mysql;

private $result;

// constructor

public function __construct($mysql,$result){

$this->mysql=$mysql;

$this->result=$result;

}

// public 'fetchRow()' method

public function fetchRow(){

return mysql_fetch_array($this->result,MYSQL_ASSOC);

}

// public 'count()' method

public function countRows(){

if(!$rows=mysql_num_rows($this->result)){

throw new Exception('Error counting rows');

}

return $rows;

}

// public 'get_insertId()' method

public function getInsertId(){

if(!$insId=mysql_insert_id($this->mysql->conId)){

throw new Exception('Error getting insert ID');

}

return $insId;

}

// public 'seek()' method

public function seekRow($row=0){

if(!is_int($row)&&$row<0){

throw new Exception('Invalid row parameter');

}

if(!$row=mysql_data_seek($this->mysql->conId,$row)){

throw new Exception('Error seeking row');

}

return $row;

}

// public 'getAffectedRows()' method

public function getAffectedRows(){

if(!$rows=mysql_affected_rows($this->mysql->conId)){

throw new Exception('Error counting affected rows');

}

return $rows;

}

}

try{

// connect to MySQL

$db=new MySQL(array('host'=>'host','user'=>'user','password'=>'pass','database'=>'database'));

$id=!$_GET['id']?1:$_GET['id'];

// run query

$result=$db->query("SELECT firstname,lastname,email,comments FROM users WHERE id='$id'");

// display user information

$row=$result->fetchRow();

if($result->countRows()==1){

echo '<h2>User Information</h2>';

echo '<p><strong>First Name: </strong>'.$row['firstname'].'</p>';

echo '<p><strong>Last Name: </strong>'.$row['lastname'].'</p>';

echo '<p><strong>Email: </strong>'.$row['email'].'</p>';

echo '<p><strong>Comments: </strong>'.$row['comments'].'</p>';

}

}

catch(Exception $e){

echo $e->getMessage();

exit();

}

?>

In addition to the source files listed above, below I included an illustrative image that shows how the details of a particular user are displayed on the same web page, instead of opening a new window:

Final thoughts

That's all for now. In this third installment of the series, you hopefully learned how to use click interceptions to extend the existing functionality of a small MySQL-driven web application.

Nevertheless, this educational journey hasn't finished yet, since in its last chapter, I'll show you how to utilize click interceptions to display the contents of different text files on a unique web page container.

Don't miss the next part!

DISCLAIMER: The content provided in this article is not warranted or guaranteed by Developer Shed, Inc. The content provided is intended for entertainment and/or educational purposes in order to introduce to the reader key ideas, concepts, and/or product reviews. As such it is incumbent upon the reader to employ real-world tactics for security and implementation of best practices. We are not liable for any negative consequences that may result from implementing any information covered in our articles or tutorials. If this is a hardware review, it is not recommended to open and/or modify your hardware.

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