Cow Computing

Often time, one might be using cURL to perform some post/get operations. Out of all, there’s a scenario where one might want to do a form post and have the user redirected thru the 302 status code issued by the server. This can be easily implemented using cURL, however, there’s a problem — The address bar doesn’t update to the redirected URL. (e.g. Posting a form from “form.php”, and redirected to “result.php”, but then the browser’s address bar remains showing “form.php”).

In order to solve the above problem, here’s a little trick:

<?php

// post param
$param = array('data' => 'abc');

$c = curl_init();
curl_setopt($c, CURLOPT_URL, "form.php");
curl_setopt($c, CURLOPT_POST, true);
curl_setopt($c, CURLOPT_POSTFIELDS, $param);
curl_setopt($c, CURLOPT_HEADER, 1);
curl_setopt($c, CURLOPT_FOLLOWLOCATION, true);
curl_exec($c);

// here's the trick
$redirectLocation = curl_getinfo($c, CURLINFO_EFFECTIVE_URL);
header("Location: $redirectLocation");

?>

Ever get stuck in deciding whether to use white list or black list during application development? Imagine, when you have to create an user management module, where certain users would have more access than the others. Will you pick white list or black list when you are writing the logic? e.g.

White List

<?php

// White List
// userid from 1 to 10
if ($userid == 1 || 3 || 5) {
// then allow access to manager admin module
} else {
// normal member module
}

?>

Read More / Comment »

Often time, when working on a website, certain database transactions have to be taken with great care (e.g. payment, account creation…). It’s definitely an advantage to make use of the Atomicity the database provides (e.g. mySQL). But How? Here’s i will show you how to use PDO to wrap a SQL insert statement such that it’s either done or no. (*it’s included with PHP5, and you have to enable the extension inside the php.ini)

<?php

$hostname = 'localhost';
$username = 'username';
$password = 'password';

try {
$dbh = new PDO("mysql:host=$hostname;dbname=mysql", $username, $password);

// Setting the notification to throw exception when error encountered
$dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

$dbh->beginTransaction();
$count = $dbh->exec("INSERT INTO user(userID, name) VALUES ('1', 'Steve')");
$dbh->commit();

$dbh = null;
}
catch(PDOException $e)
{
$dbh->rollback();
echo $e->getMessage();
}

?>

Often, to find a file with a particular extension or naming pattern within a directory, we might implement as below:

// The directory which search would be conducted
File directoryForSearch = new File("C:\folder");

// This may not be the best way to accomplish the task, please bear me with it
File[] allFile = directoryForSearch.listFiles();
File[] resultFile = new File[allFile.length];
int resultCount = 0;

// loop thru the list of files to find the required files
for(int i=0; i<allFile.length; i++)
{
    if(allFile[i].getName().matches(".*\\.java")
    {
        resultFile[resultCount] = allFile[i];
        resultCount++;
    }
}

Read More / Comment »

As we all know, HTML 5 is on its way, and there’s going to be a huge addition to the current syntax. In this post, i shall share with you about the “nth-child” feature. Often, we would like to create a table or list with alternate row color as follow:

// HTML Snippet
<div id="test-area">
  <ul>
    <li>row 1</li>
    <li class="even-row">row 2</li>
    <li>row 3</li>
    <li class="even-row">row 4</li>
    <li>row 5</li>
    <li class="even-row">row 6</li>
    <li>row 7</li>
    <li class="even-row">row 8</li>
    <li>row 9</li>
    <li class="even-row">row 10</li>
  </ul>
</div>

// CSS Snippet
ul {
  list-style: none;
}

// color the even rows
.even-row {
  background-color: #ccc;
}

Read More / Comment »