Busting The Loop Lies

“The Loop” lies to us all, don’t let it trick you. An intervention with the loop is past due. Lets walk through mastering its evil ways together. What is the best way to loop? Should you use get_posts, WP_Query or query_posts? Why does pagination break? How do you loop at all and what is the loop? How can you optimize the loop and decrease load time? Get the most out of the loop! In this talk we will master the backbone of WordPress. Together and answer these important and overlooked questions in turn.

Schedule:
http://2013.birmingham.wordcamp.org/session/busting-the-loop-lies/

Links:
http://wordpress.tv/2013/03/15/andrew-nacin-wp_query-wordpress-in-depth/
http://wordpress.stackexchange.com/questions/1753/when-should-you-use-wp-query-vs-query-posts-vs-get-posts
http://codex.wordpress.org/Function_Reference/WP_Query
http://codex.wordpress.org/Plugin_API/Action_Reference/pre_get_posts

Transcript

1. Busting The Loop Lies Kevin Dees Robojuice Sunday, August 25, 13
2. #looplies Sunday, August 25, 13
3. Why do you need to know “The Loop” Lies? Sunday, August 25, 13
4. The very basics.... What is “The Loop” Sunday, August 25, 13
5. <?php if (have_posts()) : ?> <?php while (have_posts()) : the_post(); ?> <h1><?php the_title(); ?></h1> <?php the_content();?> <?php endwhile; ?> <?php endif; ?> Sunday, August 25, 13
6. The very basics.... Where “The Loop” comes from Sunday, August 25, 13
7. “The Loop”Lives in Your Template Files Sunday, August 25, 13
8. index.php archive.php 404.php home.php Sunday, August 25, 13
9. What are “The Loop” Lies? Sunday, August 25, 13
10. “The Loop” is hard! LIE Sunday, August 25, 13
11. <?php if (have_posts()) : ?> <?php while (have_posts()) : the_post(); ?> <h1><?php the_title(); ?></h1> <?php the_content();?> <?php endwhile; ?> <?php endif; ?> Sunday, August 25, 13
12. The Main Loop vs Everything else Sunday, August 25, 13
13. $wp_query Sunday, August 25, 13
14. $wp_the_query Sunday, August 25, 13
15. NEVER USE IT Sunday, August 25, 13
16. A puppy dies every time you use it Sunday, August 25, 13
17. The Main Loop // wp-settings.php around line 220 $wp_the_query = new WP_Query(); $wp_query = $wp_the_query; Sunday, August 25, 13
18. Everything else // includes folder post.php around line 1627 function get_posts($args = null) { // lots of code $get_posts = new WP_Query; return $get_posts->query($r); } Sunday, August 25, 13
19. 4 common ways to use “The Loop” Sunday, August 25, 13
20. 4 common lies about them Sunday, August 25, 13
21. query_posts is great LIE Sunday, August 25, 13
22. It is used to edit the main loop Sunday, August 25, 13
23. <?php query_posts( array( 'posts_per_page' => 5 ); while ( have_posts() ) : the_post(); echo '<li>'; the_title(); echo '</li>'; endwhile; wp_reset_query(); ?> Sunday, August 25, 13
24. NEVER USE IT Sunday, August 25, 13
25. You run the main query twice Sunday, August 25, 13
26. You break pagination Sunday, August 25, 13
27. A puppy dies every time you use it Sunday, August 25, 13
28. get_posts uses foreach so don’t touch it LIE Sunday, August 25, 13
29. <?php $theposts = get_posts( $args ); foreach($theposts as $post) : setup_postdata($post); ?> <h2> <?php the_title(); ?> </h2> <?php endforeach; wp_reset_postdata(); ?> Sunday, August 25, 13
30. WP_Query is too verbose to use LIE Sunday, August 25, 13
31. function get_last_five() { $last_five = new WP_Query( array( 'post_type' => 'any', 'posts_per_page' => 5 )); if ( $last_five->have_posts() ) { while ( $last_five->have_posts() ) { $last_five->the_post(); $title = get_the_title(); echo "<p>{$title}</p>"; } } wp_reset_postdata(); } Sunday, August 25, 13
32. pre_get_posts is confusing LIE Sunday, August 25, 13
33. <?php add_action( 'pre_get_posts', 'demo_main_loop' ); function demo_main_loop($query) { if ( $query->is_main_query() && !is_admin() ) : // do stuff endif; return; } ?> Sunday, August 25, 13
34. // do stuff if ( is_home() ) { $query->set('post_type', 'any'); $query->set('posts_per_page', 3); } Sunday, August 25, 13
35. “The Loop” lacks powerful selection LIE Sunday, August 25, 13
36. Sunday, August 25, 13
37. // do stuff $meta_args = array( array( 'key' => 'demo_on_home_page', 'value' => 1 ) ); if ( is_home() ) { $query->set('post_type', 'any'); $query->set('meta_query', $meta_args); $query->set('posts_per_page', 3); } Sunday, August 25, 13
38. “The Loop” only runs 1 query LIE Sunday, August 25, 13
39. 4 queries are run Sunday, August 25, 13
40. 1 : the posts 2 : number of posts 3 : meta data 4 : taxonomy data Sunday, August 25, 13
41. <?php $numq = 0; add_filter('query', 'numQ'); function numQ($q) { global $numq; $numq++; return $q; } echo $numq; ?> Sunday, August 25, 13
42. Can you have just 1 query? Sunday, August 25, 13
43. global $numq; $last_five = new WP_Query( array( 'post_type' => 'any', 'posts_per_page' => 2, 'no_found_rows' => true, // rows 'update_post_meta_cache' => false, // meta 'update_post_term_cache' => false // tax )); // the loop echo “<h1>Total Queries: {$numq}</h1>”; Sunday, August 25, 13
44. if ( $last_five->have_posts() ) { echo "<h3>Last Posted Items</h3><ul>"; while ( $last_five->have_posts() ) { $last_five->the_post(); $title = get_the_title(); $link = get_permalink(); echo "<li><a href='{$link}'>{$title}</a></li>"; } echo "</ul>"; } Sunday, August 25, 13
45. Thank You Sunday, August 25, 13