The document discusses various ways that developers commonly do things wrong in WordPress development and provides recommendations for doing them right. Some of the common mistakes discussed include not upgrading WordPress, hard-coding paths, not validating user input, not using caching, and not contributing back to the WordPress community. The document provides alternatives and resources for properly enqueueing scripts, using template tags, validating data, utilizing caching, and contributing to WordPress.

1. YOU’RE DOING IT WRONG
Chris Scott - @chrisscott - slideshare.net/iamzed
photo from http://www.richardpettinger.com/funny/funny_road_signs/funny_road_signs

2. Thanks
• Dion Hulse’s (DD32) two part series on doing it
wrong:
• http://dd32.id.au/2009/11/01/youre-doing-it-wrong-1/
• http://dd32.id.au/2009/11/01/youre-doing-it-wrong-2/
• http://dd32.id.au/2009/11/24/how-to-do-it-right-part-0/
• Michael Pretty for ideas and telling me what I’m doing
wrong
• Sean O’Shaughnessy for ideas and graphics

3. New Features in a Year:
2.7 - 2.9.1
• Post thumbnails
• Sticky posts
• Comment threading and paging
• Widgets API
• Load scripts minified by default
• Load scripts in the footer
• esc_* functions
• security fixes
• and much more...

4. Wrong and Right
photo from Current Configuration

5. Not Upgrading
WRONG

6. Upgrading
RIGHT

7. Resources
• CTFB:
• Upgrade manually:
http://codex.wordpress.org/Upgrading_WordPress
• Upgrade with SVN:
http://codex.wordpress.org/Installing/Updating_WordPress_with_Subversion

8. Calling Functions That
Don’t Exist
<div id="sidebar" role="complementary">
<ul>
<li><?php wp_ozh_wsa('mybanner') ?></li>
... rest of sidebar ...
</ul>
</div>
WRONG

9. Check for Functions Before
Calling
<div id="sidebar" role="complementary">
<ul>
<?php if (function_exists('wp_ozh_wsa')) : ?>
<li><?php wp_ozh_wsa('mybanner') ?></li>
<?php endif; ?>
... rest of sidebar ...
</ul>
</div>
RIGHT

10. Hard-Coding WordPress
Paths
$cb_path = get_bloginfo('wpurl')."/wp-content/
plugins/wp-codebox"; //URL to the plugin directory
WRONG

11. Use Constants or Helper
Functions
$cb_path = plugins_url('', __FILE__); //URL to the
plugin directory
RIGHT

12. Resources
• Moving wp-content/wp-plugins:
http://codex.wordpress.org/Editing_wp-config.php#Moving_wp-content
• Stylesheet paths:
http://codex.wordpress.org/Function_Reference/get_stylesheet_directory
http://codex.wordpress.org/Function_Reference/get_stylesheet_directory_uri
• Theme paths:
http://codex.wordpress.org/Function_Reference/get_template_directory
http://codex.wordpress.org/Function_Reference/get_template_directory_uri

13. Echoing Scripts/CSS in
Header/Footer
function codebox_header() {
$hHead .= "<script language="javascript" type=
"text/javascript" src="".get_bloginfo('wpurl')."/
wp-includes/js/jquery/jquery.js"></script>n";
$hHead .= "<script language="javascript" type=
"text/javascript" src="{$cb_path}/js/codebox.js"
></script>n";
print($hHead);
}
add_action('wp_head', 'codebox_header');
WRONG

14. Enqueue Scripts and Styles
function codebox_header() {
wp_enqueue_script(
'codebox',
plugins_url('js/ codebox.js', __FILE__),
array('jquery')
);
}
add_action('template_redirect', 'codebox_header');
RIGHT

15. Resources
• wp_enqueue_script:
http://codex.wordpress.org/Function_Reference/wp_enqueue_script
• wp_enqueue_style:
http://codex.wordpress.org/Function_Reference/wp_enqueue_style
• Enqueueing styles with conditionals:
http://iamzed.com/using-wordpress-wp_enqueue_style-with-conditionals/
• Plugin API/Action Reference:
http://codex.wordpress.org/Plugin_API/Action_Reference

16. Not Checking Indices or
Object Properties
if ($_GET['wp125action'] == "deactivate") {
...
}
WRONG

17. Checking Indices/Properties
if (isset($_GET['wp125action']) && $_GET
['wp125action'] == "deactivate") {
...
}
RIGHT

18. Resources
• isset():
http://php.net/isset
• empty():
http://php.net/emtpy

19. Not Using WP_DEBUG
WRONG

20. Define WP_DEBUG in
wp-config.php
define('WP_DEBUG', true);
RIGHT

21. Resources
• WP_DEBUG:
http://codex.wordpress.org/Editing_wp-config.php#Debug
• Use dev versions of WP scripts:
define('SCRIPT_DEBUG', true);
• Disable admin js concatenation:
define('CONCATENATE_SCRIPTS', false);

22. Using Globals Instead of
Template Tags
global $post;
$title =$post->post_title;
WRONG

23. Use Template Tags
$title = get_the_title();
RIGHT

24. Resources
• Template Tags:
http://codex.wordpress.org/Template_Tags

25. Writing SQL
global $wpdb;
$wpdb->query("update ".$articles." set review = ".
$rating." where post_id = ".$post_id);
WRONG

26. Use $wpdb Methods
global $wpdb;
$wpdb->update(
$articles,
array('review' => $rating),
compact('post_id')
);
RIGHT

27. Resources
• wpdb Class:
http://codex.wordpress.org/Function_Reference/wpdb_Class
• wpdb->prepare():
http://codex.wordpress.org/Function_Reference/
wpdb_Class#Protect_Queries_Against_SQL_Injection_Attacks

28. Not Validating/Escaping
User Input
<label for="title"><?php echo get_option
('my_plugin_option_title'); ?></label>
<input type="text" id="value" name="value" value="<?
php echo get_option('my_plugin_option_value')); ?>">
WRONG

29. Validate and Escape User
Input
<label for="title"><?php echo esc_html(get_option
('my_plugin_option_title')); ?></label>
<input type="text" id="value" name="value" value="<?
php echo esc_attr(get_option
('my_plugin_option_value')); ?>">
RIGHT

30. Resources
• Data validation:
http://codex.wordpress.org/Data_Validation
• wpdb->prepare():
http://codex.wordpress.org/Function_Reference/
wpdb_Class#Protect_Queries_Against_SQL_Injection_Attacks

31. Not Using Caching
$response = wp_remote_get($url);
if (!is_wp_error($response)
&& $response['response']['code'] == '200')
{
$data = $response['body'];
}
... do something with data ...
WRONG

32. Use Caching
if (!$data = wp_cache_get('my_external_data')) {
$response = wp_remote_get($url);
if (!is_wp_error($response) &&
$response['response']['code'] == '200')
{
$data = $response['body'];
wp_cache_set('my_external_data', $data);
}
}
... do something with data ...
RIGHT

33. Resources
• WP_Cache:
http://codex.wordpress.org/Function_Reference/WP_Cache

34. Not Contributing
photo by TaranRampersad http://www.flickr.com/photos/knowprose/2294744043/
WRONG

35. Contributing
http://codex.wordpress.org/
Contributing_to_WordPress
• Edit the Codex
• Answer Forum Support Questions
• Participate in Development
• Planning, Testing, Bug Reporting and Fixing
• Say “Thanks”
RIGHT