For seasoned developers approaching WordPress customization or development for the first time the biggest challenge is often not learning the API and method calls: it's grasping the idiosyncrasies of the WordPress framework. In this 45-minute presentation aimed at web coders who are interested in diving into WordPress customization and development, you will learn the key idioms that will accelerate your learning curve and help you approach the framework from a best practices perspective: template hierarchies, themes and child themes, taxonomies, filters and action hooks, execution order and other need-to-know concepts will be presented as well as tips on what the most active online developer communities are and the best places to go for quick (free) help and advice.

1. WordPress Development Paradigms, Idiosyncrasies and Other Big Words Tom Auger, Zeitguys inc. WordCamp Montreal, 2011

23. Paradigm: Themes and Templates

31. Paradigm: Hooks, Actions and Filters

37. Action examples add_action('init', 'register_my_custom_post'); add_action('init', 'register_my_custom_taxonomy'); add_action('widgets_init', 'register_my_widget'); add_action('wp_enqueue_scripts', 'add_my_js_libs'); add_action('save_post', 'save_my_custom_meta');

40. Filter Examples add_filter( 'excerpt_more', 'custom_more' ); add_filter( 'excerpt_length', 'my_length', 999 ); function my_length($length){ return 6; // six is average, right? }

44. Idiom: The Loop and The Query

50. Idiosyncrasy: $wpdb

53. Pure SQL select * from wp_posts join wp_term_relationships on ID = object_id join wp_term_taxonomy on wp_term_taxonomy.term_taxonomy_id = wp_term_relationships.term_taxonomy_id and taxonomy = 'event-type' join wp_terms on wp_term_taxonomy.term_id = wp_terms.term_id and wp_terms.slug = 'speaking' join wp_postmeta on wp_postmeta.post_id = ID and meta_key = 'event-date' and meta_value = '2011-07-09' where post_type = 'event' and post_status = 'published'

54. More Properer SQL select * from wp_posts as P join wp_term_relationships TR_EVENT on P .ID = TR_EVENT .object_id join wp_term_taxonomy TT_EVENT on TT_EVENT .term_taxonomy_id = TR_EVENT .term_taxonomy_id TT_EVENT .taxonomy = 'event-type' join wp_terms T_EVENT on TT_EVENT .term_id = T_EVENT .term_id and T_EVENT .slug = 'speaking' join wp_postmeta M_DATE on M_DATE .post_id = P.ID and M_DATE .meta_key = 'event-date' and M_DATE .meta_value = '2011-07-09' where P .post_type = 'event' and P .post_status = 'published'

55. Don't Use Table Names! select * from {$wpdb->posts} P join {$wpdb->term_relationships} TR_EVENT on P.ID = TR_EVENT.object_id join {$wpdb->term_taxonomy} TT_EVENT on TT_EVENT.term_taxonomy_id = TR_EVENT.term_taxonomy_id TT_EVENT.taxonomy = 'event-type' join {$wpdb->terms} T_EVENT on TT_EVENT.term_id =T_EVENT.term_id and T_EVENT.slug = 'speaking' join {$wpdb->postmeta} M_DATE on M_DATE.post_id = P.ID and M_DATE.meta_key = 'event-date' and M_DATE.meta_value = '2011-07-09' where P.post_type = 'event' and P.post_status = 'published'

56. More Saferer Query $wpdb->prepare ("select * from {$wpdb->posts} P join {$wpdb->term_relationships} TR_EVENT on P.ID = TR_EVENT.object_id join {$wpdb->term_taxonomy} TT_EVENT on TT_EVENT.term_taxonomy_id = TR_EVENT.term_taxonomy_id TT_EVENT.taxonomy = 'event-type' join {$wpdb->terms} T_EVENT on TT_EVENT.term_id =T_EVENT.term_id and T_EVENT.slug = %s join {$wpdb->postmeta} M_DATE on M_DATE.post_id = P.ID and M_DATE.meta_key = 'event-date' and M_DATE.meta_value = %s where P.post_type = 'event' and P.post_status = 'published'", 'speaking', '2011-07-09' );

57. But, Whenever We Can... get_posts(array( 'post_type' => 'event', 'tax_query' => array(array( 'taxonomy' => 'event-type', 'field' => 'slug' 'terms' => 'speaking' )), 'meta_query' => array(array( 'key' => 'event-date', 'value' => $todays_date )) ));

59. Idiosyncrasy: wp_enqueue_script

64. Thanks! www.tomauger.com www.zeitguys.com @TomAuger

65. Other Stuff for more time

66. Paradigm: Post Types and Taxonomies