Symfony – Manipulating Database Sessions

The default Symfony session storage writes the session information to files. Most medium to large websites use a database to store the session values instead of files, because databases are easier to use and scale in a multiple web server environment.

Symfony has a built-in solution for database session storage called PdoSessionHandler.

You can read the article here to Use PdoSessionHandler to Store Sessions in the Database Here.

 

AccessUsers in Session Data

You can also decode, access and modify user session data easily, since it’s now stored in the database. This means you could get stats from logged in users, queue notifications for users, check certain types of history.. stuff like that.

Here’s an example command which prints out a list and count of users who have been active in the last 10 minutes:

<?php

// src/Your/Bundle/Command/SessionsCheckCommand.php
namespace Your\Bundle\Command;

use Symfony\Bundle\FrameworkBundle\Command\ContainerAwareCommand;
use Symfony\Component\Console\Input\InputInterface;
use Symfony\Component\Console\Output\OutputInterface;

class SessionsCheckCommand extends ContainerAwareCommand
{
    protected function configure()
    {
        $this
          ->setName('sessions:check')
          ->setDescription('Checks user activity for the past couple of minutes and prints out some stats');
    }

    protected function execute(InputInterface $input, OutputInterface $output)
    {
        $threshold = 600; // Maximum seconds for last activity
        $limit = time() - $threshold;

        $em = $this->getContainer()->get('doctrine.orm.entity_manager');

        $dql = 'select s from YourBundle:Session s
            where s.sessionTime >= ?1
            order by s.sessionTime desc';
        $query = $em->createQuery($dql);
        $query->setParameter(1, $limit);
        $sessions = $query->getResult();

        $active_users = array();                // Names of active users
        $total_active_count = count($sessions); // Total active users
        $total_active_auth_count = 0;           // Total active logged in users

        foreach ($sessions as $session) {
            $data =$session->getSessionValue();
            $data = str_replace('_sf2_attributes|', '', $data);
            $data = unserialize($data);

            // If this is a session belonging to an anonymous user, do nothing
            if (!array_key_exists('_security_main', $data)) continue;

            // User is logged in, increment counter
            $total_active_auth_count++;

            // Grab security data
            $data = $data['_security_main'];
            $data = unserialize($data);

            // Add username to activity list
            $active_users[] = $data->getUser()->getUsername();
        }

        $output->writeln('The following users were active in the past few minutes:');
        $output->writeln(join(', ', $active_users));

        $output->writeln(sprintf(
            '%s user(s) were active, and %s of them was/were logged in.',
            $total_active_count,
            $total_active_auth_count
        ));
    }
}

PHP – Introduction

What is PHP?

PHP is a server scripting language, and a powerful tool for making dynamic and interactive Web pages. PHP is a widely-used, free, and efficient alternative to competitors such as Microsoft’s ASP.

  • Serverside scripting language
  • Used for web development
  • Generate dynamic web pages

Requirements

What you will need?

  • Computer with PHP installed
  • Text editing application
  • A web browser

What would be helpful?

  • Understanding of HTML
  • Understanding of programming concept
  • Understanding how web server works

Terminologies 

Hypertext

Hypertext is text that links to other information. By clicking on a link in a hypertext document, a user can quickly jump to different content.

Preprocessor

In computer science, a preprocessor is a program that processes its input data to produce output that is used as input to another program. The output is said to be a preprocessed form of the input data, which is often used by some subsequent programs like compilers.

Serverside Scripting Language

Those scripts were executed by the operating system, and the results were served back by the web server. Many modern web servers can directly execute on-line scripting languages such as ASP, JSP, Perl, PHP and Ruby either by the web server itself or via extension modules (e.g. mod_perl or mod_php) to the web server.

HTML

HyperText Markup Language (HTML) is the standard markup language for creating web pages and web applications. With Cascading Style Sheets (CSS), and JavaScript, it forms a triad of cornerstone technologies for the World Wide Web.

HTTP

A Web server is a program that uses HTTP (Hypertext Transfer Protocol) to serve the files that form Webpages to users, in response to their requests, which are forwarded by their computers’ HTTP clients.

Web Development

Web development broadly refers to the tasks associated with developing websites for hosting via intranet or Internet. The Web development process includes Webdesign, Web content development, client-side/server-side scripting and network security configuration, among other tasks.

Dynamic Webpage

A dynamic web page is a web page that displays different content each time it’s viewed. For example, the page may change with the time of day, the user that accesses the webpage, or the type of user interaction.

 

web server working
web server working

 

Common uses of PHP

  • PHP performs system functions, i.e. from files on a system it can create, open, read, write, and close them.
  • PHP can handle forms, i.e. gather data from files, save data to a file, through email you can send data, return data to the user.
  • You add, delete, modify elements within your database through PHP.
  • Access cookies variables and set cookies.
  • Using PHP, you can restrict users to access some pages of your website.
  • It can encrypt data.

Characteristics of PHP
Five important characteristics make PHP’s practical nature possible −

  1. Simplicity
  2. Efficiency
  3. Security
  4. Flexibility
  5. Familiarity

“Hello World” Script in PHP

To get a feel for PHP, first start with simple PHP scripts. Since “Hello, World!” is an essential example, first we will create a friendly little “Hello, World!” script.

As mentioned earlier, PHP is embedded in HTML. That means that in amongst your normal HTML (or XHTML if you’re cutting-edge) you’ll have PHP statements like this −

<html>
   
   <head>
      <title>Hello World</title>
   </head>
   
   <body>
      <?php echo "Hello, World!";?>
   </body>

</html>

It will produce following result −

Hello, World!