This document discusses using WordPress as a web application framework. It outlines reasons for and against using WordPress, including that it is stable, supported by a large community, and scales well, but also has some code debt and uses PHP. It then explains how to build applications with WordPress, including using actions and filters, developing a JSON API, integrating jQuery and Backbone, leveraging the template hierarchy, and using custom post types and metadata. It also provides examples of caching external API requests and using transients.

1. Using WordPress as
your application stack
WHY AND HOW

2. @me
Senior Full Stack WordPress Developer
Plugin author of Author Avatars List http://wordpress.org/plugins/author-avatars/
and WP Site Verification tool http://wordpress.org/plugins/wp-site-verification-tool/
Slides @ http://www.slideshare.net/pbearne

3. Why WordPress?
•Stable
•Supported
•Community
•Scales

4. Why not WordPress?
•Code debt
•PHP
•Has PHP global’s
•Not sexy

5. 23%
OF THE SITES IN WHOLE INTERNET

6. 34,000
PLUG-INS

7. 2,800
THEMES

8. How
•Actions and filters
•JSON API
•jQuery - Backbone
•Template hierarchy
•Custom post types

9. Filter
add_filter(‘fliter_name’, ‘function_to_run’);
Function function_to_run( $var ){
$var .= ‘hello world’;
return $var;
}
http://codex.wordpress.org/Plugin_API#Filters

10. Action
add_action(‘action_name’, ‘function_to_run’);
Function function_to_run( $var = null ){
echo ‘hello world’;
}
http://codex.wordpress.org/Plugin_API#Actions

11. Ajax Route
/**
* Register a rewrite endpoint for the API.
*/
function prefix_add_api_endpoints() {
add_rewrite_tag( '%api_item_id%', '([0-9]+)' );
add_rewrite_rule( 'api/items/([0-9]+)/?',
'index.php?api_item_id=$matches[1]', 'top' );
}
add_action( 'init', 'prefix_add_api_endpoints' );
https://10up.github.io/Engineering-Best-Practices/php/#ajax-endpoints

12. Ajax handler
function prefix_do_api() {
global $wp_query;
$item_id = $wp_query->get( 'api_item_id' );
if ( ! empty( $item_id ) ) {
$response = array();
// Do stuff with $item_id
wp_send_json( $response );
}
}
add_action( 'template_redirect', 'prefix_do_api' );

13. JSON API wordpress.com
Part of the Jetpack plug-in
http://developer.wordpress.com/docs/api/
https://developer.wordpress.com/docs/api/console/
End point
https://public-api.wordpress.com/rest/v1/
e.g.
https://public-api.
wordpress.com/rest/v1/sites/authoravatars.wordpress.com/

14. JSON API wp.org (self host)
Part of next version of core (currently plug-in)
http://wp-api.org/
End point
https://domain.com/wp-json/

15. JSON API wp-api.org/ v. WP.com
WP.com
Wp-api.org
Caching
On you server
Little load on your servers
Extendable
Access to WordPress.com user and stats
More complete
The API’s don’t match (yet)

16. BackBone
Included with WordPress 
To just load it
wp_enqueue_script( ‘backbone’ );
Or better still load as a dependency of your script
wp_enqueue_script( ‘myscript’, ‘path/to/script, array( 'backbone' ) );
https://github.com/tlovett1/_s_backbone

17. Template Hierarchy
The order Wordpress load its template files
http://codex.wordpress.org/Template_Hierarchy

18. Template Hierarchy

19. Custom post types
The main logical data object
in WordPress
The standard types are :
post, page, media
add_action( 'init', 'create_post_type' );
function create_post_type() {
register_post_type(
'acme_product',
array( 'labels' => array(
'name' => __( 'Products' ),
'singular_name' => __( 'Product' )
),
'public' => true,
'has_archive' => true, )
);
}
http://codex.wordpress.org/Post_Types

20. Custom metadata
The data linked to a post object
Text or serialized data
Use CMB2 to easily create admin forms
Hide the metadata from admin by
starting the id with an “_”
$meta_boxes[ 'tombstone_page_metabox' ] = array(
'id' => __( 'tombstone_page_metabox',
Config::get_text_domain() ),
'title' => __( 'Tombstone Details',
Config::get_text_domain() ),
'object_types' => array( self::get_tombstone_post_type() ),
https://github.com/WebDevStudios/CMB2
// Post types
'context' => 'normal',
'priority' => 'high',
'show_names' => true, // Show field names on the left
'fields' => array(
array(
'name' => __( 'Tag line', Config::get_text_domain()
),
'desc' => __( 'Enter the pull Quote',
Config::get_text_domain() ),
'id' => Config::_get_prefix() . 'tagline',
'type' => 'textarea_small',
'attributes' => array(
'style' => 'width:100%;',
),
),
)
);

21. Call external API and cache
Use the internal
wp_remote_get() get remote data.
Then cache the data with a
transients cache
or
tlc_transient()
$request = wp_remote_get('http://example.com');
$response = wp_remote_retrieve_body( $request );
echo $response;
<?php
// Define your callback (other examples use
this)
function my_callback() {
return wp_remote_retrieve_body(
wp_remote_get( 'http://example.com/feed.xml',
array( 'timeout' => 30 ) )
);
} // Grab that feed echo
$data = tlc_transient( 'example-feed' )
->updates_with( 'my_callback' )
->expires_in( 300 )
->get();
If( false != $data ){
// show data
}
?>
https://github.com/markjaquith/WP-TLC-Transients

22. Questions?
http://www.slideshare.net/pbearne