Web Coding & Development All-in-One For Dummies
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All web apps perform a number of chores at the beginning of any task. On the back end, these initialization chores include starting a user session and connecting to the database, and on the front end the startup includes outputting the app's common HTML (especially the section) and including the app’s common components, such as a header and footer.

Rather than repeating the code for these startup chores in every file, you should create two files — one for the back end initialization and one for the front end’s common code — and then include the files as you begin each web app task.

Creating the back-end initialization file

When performing any task, a typical web app must first run through a number of back-end chores, including the following:
  • Setting the error reporting level
  • Starting a session for the current user, if one hasn’t been started already
  • Creating a token for the session
  • Including common files, such as a file of constants used throughout the app
  • Connecting to the database, if the app uses server data
You should store this file in your web app’s private/common/ directory.:

// Start a session session_start();

// Have we not created a token for this session, // or has the token expired? if (!isset($_SESSION['token']) || time() > $_SESSION['token_expires']){ $_SESSION['token'] = bin2hex(openssl_random_pseudo_bytes(16)); $_SESSION['token_expires'] = time() + 900; $_SESSION['log_id'] = 1; }

// Include the app constants include_once 'constants.php';

// Connect to the database $mysqli = new MySQLi(HOST, USER, PASSWORD, DATABASE);

// Check for an error if($mysqli->connect_error) { echo 'Connection Failed! Error #' . $mysqli->connect_errno . ': ' . $mysqli->connect_error; exit(0); } ?>

This code cranks up the error reporting to 11 for the purposes of debugging, starts a new session, creates a session token (if needed), includes the constants file (which contains the database credentials), and then connects to the database and creates a MySQLi object. Note, too, that $_SESSION['log_id'] was set to 1, but this is temporary.

You want to use error_reporting(E_ALL | E_STRICT) when you’re developing your web app because you want the PHP processor to let you know when something’s amiss, either as an error (E_ALL) or as non-standard PHP code (E_STRICT). However, you certainly don't want your app’s users to see these errors or warnings, so when you’re ready for your web app to go live, edit initialization.php to follow this statement:

error_reporting(E_ALL | E_STRICT)
with these statements:
ini_set('display_errors', 0);
ini_set('log_errors', 1);
ini_set('error_log', '../private/logs/error_log');
These statements configure PHP to not display errors onscreen, but to log them to a file, the name and path of which is specified in the final statement.

Creating the front-end common files

Each page of your web app has a common structure. For example, the top part of each page includes the following elements:
  • The DOCTYPE and the tag
  • The head element, including the tags, page title, CSS tags, and JavaScript
    In this code, note that the page title is given by the following inline PHP:
    The idea here is that each page will set the $page_title variable just before including top.php, which enables you to define a custom title for each page. For example, the home page might do this:
    Note that this same title also gets inserted in the page header element, within the

    tag.

    Most web apps also include a sidebar — defined by an

    closing tag, a footer, and the and closing tags. For this code, create a separate file called, say, public\common\bottom.php and add your code:
      
    Copyright Your Name
    The footer uses the PHP statement echo date('Y') to output the current year for the Copyright notice. This file also adds references to the app's two external JavaScript files: data.js and user.js. Adding these at the bottom of the page (instead of the usual place in the page's head section) ensures that your JavaScript code can work with the elements added to the page on the fly.

    Building the app home page

    With the initialization files in place, it’s time to build the skeleton for the app’s home page. At the moment, this page is nothing but PHP:
    ="code">
    Main app content goes here
    
    Save this file as index.php in the web root directory.

About This Article

This article is from the book:

About the book author:

Paul McFedries is a true renaissance geek. He has been a programmer, consultant, database developer, and website builder. He's also the author of more than 90 books including top sellers covering Windows, Office, and macOS.

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