Group Posts by First Letter of Title

2 comments

1. once up a time i did a client project where i had to have archives by first letter. thinking back i’m wondering if shouldn’t have just created a hidden taxonomy and then saved the first letter as a term in that taxonomy.

   anyway, here’s what i actually did:

   /*
    * Function Create Array of Letters that have post titles (for archive)
    */
   
   /* When the post is saved, saves our custom data */
   function kia_save_first_letter( $post_id ) {
       // verify if this is an auto save routine. 
       // If it is our form has not been submitted, so we dont want to do anything
       if ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE ) 
           return;
   
       //check location (only run for posts)
       $limitPostTypes = array('post');
       if (!in_array($_POST['post_type'], $limitPostTypes)) return;
   
       // Check permissions
       if ( !current_user_can( 'edit_post', $post_id ) )
           return;
   
   
       // OK, we're authenticated: we need to find and save the data
       $alphabet = get_option( 'kia_alphabet_archive' );
   
       $alphabet = is_array($alphabet) ? $alphabet : array($alphabet);
   
       // pop off first letter of post title
       $letter = substr($_POST['post_title'], 0, 1);
   
       // if it doesn't exist, add it to array
       if(!in_array($letter, $alphabet))
           $alphabet[] = $letter;
           sort($alphabet);
   
       $alphabet = is_array($alphabet) ? array_unique($alphabet) : array($alphabet);
   
       update_option( 'kia_alphabet_archive', $alphabet );
   }
   add_action( 'save_post', 'kia_save_first_letter' );
   

   if you have posts already before adding this you’ll need to run the following once to grab the first letters for the existing posts:

   //create array from existing posts
   function kia_run_once(){
       $alphabet = array();
       $posts = get_posts(array(   
               'numberposts'     => -1
               ) );
   
       foreach($posts as $p) :  
           $alphabet[] = strtoupper(substr($p->post_title, 0, 1)); //first letter of post title, capitalized 
       endforeach;
   
       sort($alphabet);
   
       update_option( 'kia_alphabet_archive', array_unique($alphabet) );
   
   }
   add_action('init','kia_run_once');
   

   now we need some stuff to decipher when were are on a custom archive page and what to do differently

   /*
    * Custom Archives by KIA
    */
   
   function archive_queryvars( $qvars ) {
       $qvars[] = 'showarchive';
       return $qvars;
   }
   add_filter('query_vars', 'archive_queryvars' );
   
   
   function is_custom_archive() {
       global $wp_query;
       return isset( $wp_query->query_vars['showarchive'] );
   }
   
   function archive_search_where( $where ){
       global $wpdb;
   
       if( is_custom_archive() ) {
           $char = get_query_var('showarchive');
           if ( ! empty($char) ) {
               $where .= "AND {$wpdb->posts}.post_title LIKE '{$char}%'";
           }
       } 
     return $where;
   }
   add_filter('posts_where', 'archive_search_where' );
   

   little helper function to make links

   /* 
    * add archive query arg to link
    */
   function get_custom_archive_link($char = '') {
       $params = array(
               'showarchive' => $char,
               );
       return add_query_arg( $params, home_url('/') );
   }
   

   now create our custom archive menu

   $alphabet = get_option ('kia_alphabet_archive');
   
   if(count($alphabet)>0){ ?>
       <div id="archive-menu" class="menu">
       <?php for ($i=65; $i < 91; $i++) : 
               $current = (chr($i) == get_query_var('showarchive')) ? "current-menu-item" : "menu-item";
   
               if (is_array($alphabet) && in_array(chr($i), $alphabet)){ ?>
                   <li class="az-char <?php echo $current;?>">
                       <?php printf('<a href="%s">%s</a>', get_custom_archive_link(chr($i)), chr($i) ) ?>
                   </li>
               <?php } else { ?>
                   <li class="az-char <?php echo $current;?>">
                       <?php echo chr($i); ?>
                   </li>
               <?php } ?>  
   
               <?php endfor; ?>
       </div>
   <?php }
   

   clicking on the links should now bring you to a page that only shows posts that state with that letter.

   ---

   looking back i think the taxonomy idea would be a lot less code and have cleaner rewrite support built-in from the beginning (ie… no query vars, even though those could be re-written… i don’t know how). the taxonomy approach would also add tax data to the DB, whereas this only adds the one option. so trade-off?

   *EDIT**

   ok, i took a stab at the taxonomy route and it is slightly more elegant like i expected

   first register the taxonomy. i have this only running on posts, but you could easily mod it to suite whatever post type you’d like.

   // Add new taxonomy, NOT hierarchical (like tags)
   function kia_create_glossary_taxonomy(){
       if(!taxonomy_exists('glossary')){
           register_taxonomy('glossary',array('post'),array(
           'show_ui' => false
         ));
        }
   }
   add_action('init','kia_create_glossary_taxonomy');
   

   similar save function to store our tax data when a post is saved

   /* When the post is saved, saves our custom data */
   function kia_save_first_letter( $post_id ) {
       // verify if this is an auto save routine. 
       // If it is our form has not been submitted, so we dont want to do anything
       if ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE ) 
           return;
   
       //check location (only run for posts)
       $limitPostTypes = array('post');
       if (!in_array($_POST['post_type'], $limitPostTypes)) return;
   
       // Check permissions
       if ( !current_user_can( 'edit_post', $post_id ) )
           return;
   
   
       // OK, we're authenticated: we need to find and save the data
       $taxonomy = 'glossary';
   
       //set term as first letter of post title, lower case
       wp_set_post_terms( $post_id, strtolower(substr($_POST['post_title'], 0, 1)), $taxonomy );
   
       //delete the transient that is storing the alphabet letters
       delete_transient( 'kia_archive_alphabet');
   }
   add_action( 'save_post', 'kia_save_first_letter' );
   

   again need to run something once to grab old posts, remove when done

   //create array from existing posts
   function kia_run_once(){
       $taxonomy = 'glossary';
   
       $alphabet = array();
       $posts = get_posts(array('numberposts' => -1) );
   
       foreach($posts as $p) :  
           //set term as first letter of post title, lower case
           wp_set_post_terms( $p->ID, strtolower(substr($p->post_title, 0, 1)), $taxonomy );
       endforeach;     
   }
   add_action('init','kia_run_once');
   

   add the menu this was the only part that wasn’t totally elegant, as it wasn’t straightforward to test whether a term had posts w/o the extra foreach loop. but i have mitigated that by storing it in a transient that only resets on post save.

   $taxonomy = 'glossary';  
   
   // save the terms that have posts in an array as a transient
   if ( false === ( $alphabet = get_transient( 'kia_archive_alphabet' ) ) ) {
       // It wasn't there, so regenerate the data and save the transient
       $terms = get_terms($taxonomy);
   
       $alphabet = array();
       if($terms){
           foreach ($terms as $term){
               $alphabet[] = $term->slug;
           }
       }
        set_transient( 'kia_archive_alphabet', $alphabet );
   }
   
   ?>
   
   <div id="archive-menu" class="menu">
       <?php foreach(range('a', 'z') as $i) : 
               $current = ($i == get_query_var($taxonomy)) ? "current-menu-item" : "menu-item";
   
               if (in_array( $i, $alphabet )){ ?>
                   <li class="az-char <?php echo $current;?>">
                       <?php printf('<a href="%s">%s</a>', get_term_link( $i, $taxonomy ), strtoupper($i) ) ?>
                   </li>
               <?php } else { ?>
                   <li class="az-char <?php echo $current;?>">
                       <?php echo strtoupper($i); ?>
                   </li>
               <?php } ?>  
   
           <?php endforeach; ?>
   </div>
   

   so there are 2 solutions. the latter will get your URLs to say site.com/glossary/l without any htaccess rules to re-write query vars on your part. hope that helps.

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2. I would suggest you to use WP_Query for this purpose. An example of this query is here in this plugin which fetches only relevant posts instead of using further PHP functions.

   You can choose a faster way to go on, Alphabetic Pagination Plugin

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