Symfony Vs Simple PHP

Simple Blog in flat PHP

you'll build the token blog application using only flat PHP. To begin, create a single page that displays blog entries that have been persisted to the database. Writing in flat PHP is quick and dirty: 
// index.php
$link = mysql_connect('localhost', 'myuser', 'mypassword');
mysql_select_db('blog_db', $link);
$result = mysql_query('SELECT id, title FROM post', $link);
?>
<!DOCTYPE html>
<html>
<head>
<title>List of Posts</title>
</head>
<body>
<h1>List of Posts</h1>
<ul>
<?php while ($row = mysql_fetch_assoc($result)): ?>

<li>
<a href="/show.php?id=<?php echo $row['id'] ?>">
<?php echo $row['title'] ?>
</a>
</li>
<?php endwhile; ?>
</ul>
</body>
</html>
<?php
mysql_close($link);
?>
DrawBacks
  • No error-checking: What if the connection to the database fails?

  • Poor organization: If the application grows, this single file will become increasingly unmaintainable. Where should you put code to handle a form submission? How can you validate data? Where should code go for sending emails?

  • Difficult to reuse code: Since everything is in one file, there's no way to reuse any part of the application for other "pages" of the blog.

    • Note :Symfony2 fully integrates Doctrine1, a library dedicated to database abstraction and mapping.

    Isolating the Presentation

    The code can immediately gain from separating the application "logic" from the code that prepares the HTML "presentation": 
    <?php
// index.php
$link = mysql_connect('localhost', 'myuser', 'mypassword');
mysql_select_db('blog_db', $link);
$result = mysql_query('SELECT id, title FROM post', $link);
$posts = array();
while ($row = mysql_fetch_assoc($result)) {
$posts[] = $row;
}
mysql_close($link);
// include the HTML presentation code
require 'templates/list.php';
    The HTML code is now stored in a separate file (templates/list.php), which is primarily an HTML file that uses a template-like PHP syntax: 
    <!DOCTYPE html>
<html>
<head>
<title>List of Posts</title>
</head>
<body>
<h1>List of Posts</h1>
<ul>
<?php foreach ($posts as $post): ?>
<li>
<a href="/read?id=<?php echo $post['id'] ?<">
<?php echo $post['title'] ?>
</a>
</li>
<?php endforeach; ?>
</ul>
</body>
</html>
    the file that contains all of the application logic - index.php - is known as a "controller" . Controller refers simply to the area of your code that processes user input and prepares the response. In this case, the controller prepares data from the database and then includes a template to present that data.

    Isolating the Application (Domain) Logic

    <?php
// model.php
function open_database_connection()
{
$link = mysql_connect('localhost', 'myuser', 'mypassword');
mysql_select_db('blog_db', $link);
return $link;
}
function close_database_connection($link)
{
mysql_close($link);
}
function get_all_posts()
{
$link = open_database_connection();
$result = mysql_query('SELECT id, title FROM post', $link);
$posts = array();
while ($row = mysql_fetch_assoc($result)) {
$posts[] = $row;
}
close_database_connection($link);
return $posts;
}
    Note :The filename model.php is used because the logic and data access of an application is traditionally known as the "model" layer. In a well-organized application, the majority of the code representing your "business logic" should live in the model.

    controller (index.php) is now very simple : 
    <?php
require_once 'model.php';
$posts = get_all_posts();
require 'templates/list.php';

    Isolating the Layout

    At this point, the application has been refactored into three distinct pieces offering various advantages and the opportunity to reuse almost everything on different pages. The only part of the code that can't be reused is the page layout. Fix that by creating a new layout.php file: 
    <!-- templates/layout.php -->
<!DOCTYPE html>
<html>
<head>
<title><?php echo $title ?></title>
</head>
<body>
<?php echo $content ?>
</body>
</html>

    The template (templates/list.php) can now be simplified to "extend" the layout:
    <?php $title = 'List of Posts' ?>
<?php ob_start() ?>
<h1>List of Posts</h1>
<ul>
<?php foreach ($posts as $post): ?>
<li>
<a href="/read?id=<?php echo $post['id'] ?>">
<?php echo $post['title'] ?>
</a>
</li>
<?php endforeach; ?>
</ul>
<?php $content = ob_get_clean() ?>
<?php include 'layout.php' ?>