How to list all categories and tags in a page?

TERM METADATA

It’s possible to get thumbnails for terms using the new Term Metadata in 4.4. You just also need to define those ahead of time yourself.

• add_term_meta( int $term_id, string $meta_key, mixed $meta_value, bool $unique = false )
• get_term_meta( int $term_id, string $key = '', bool $single = false )
• update_term_meta( int $term_id, string $meta_key, mixed $meta_value, mixed $prev_value="" )

---

CATEGORIES

get_categories ( ) Returns an array of category objects matching the query parameters.

echo "Categories:<br/>";

$args = array( 
    'orderby'                  => 'name',
    'order'                    => 'ASC', 
    'public'                   => true,
); 

$categories = get_categories( $args );

foreach ( $categories as $category ) {
     echo '<a href="' . get_category_link( $category ) . '">' . $category->name . '</a><br/>';
}

---

echo "<hr>"; // divider

---

TAGS

get_tags ( ) Retrieves an array of objects for each term in post_tag taxonomy.

echo "Tags:<br/>";

$args = array( 
    'orderby'                  => 'name',
    'order'                    => 'ASC',
    'public'                   => true,
); 

$tags = get_tags( $args );

foreach ( $tags as $tag ) {
     echo '<a href="' . get_tag_link( $tag ) . '">' . $tag->name . '</a><br/>';
}

TAXONOMIES

get_taxonomies ( ) Get a list of registered taxonomy objects.

echo "Taxonomies:<br/>";

$args = array(  
    '_builtin'                 => false, 
    'public'                   => true,
); 

$taxonomies = get_taxonomies( $args, 'objects' ); 

foreach ( $taxonomies as $taxonomy ) {
    echo '<p>' . $taxonomy->labels->name . '</p>';
}

POST TYPES

get_post_types ( ) Returns the registered post types as found in $wp_post_types. get_posts ( ) creates an array of posts based on a set of parameters so use it with your post_type_list.

echo "Post Types:<br/>";

$args = array(
    'public'   => true,
    '_builtin' => false,
);
$output="names"; // names or objects, note names is the default
$operator="and"; // 'and' or 'or'
$post_types = get_post_types($args, $output, $operator);

// get all the posts for all post_types

$posts = get_posts(array(
                           'post_type'   => $post_types,
                           'numberposts' => - 1,
                           'orderby'     => 'post_type',
                           'order'       => 'ASC',
                           'post_status' => array( 'publish' ),
                           'public'      => true,
                       ));

foreach($posts as $post) {

    $link = get_permalink($post);
    $title = $post->post_title;

    if($post_type !== $post->post_type) {
        $post_type = $post->post_type;
        echo '</br/><p>' . $post_type . '</p></br/>';
    }

    // show link to post

    echo "<p><a href=\"$link\">$title</a></p>";
}

TRANSIENT CACHING

If you want to cache the results of all these queries then consider the Transients API. This will store the result into the database for a limited time (which you ~request~). It’s not a certain timeframe because plugins like WP Optimize can clear the cache anytime.

// check if the value exists using the key -- if it fails then we'll generate the content

if(false === ($trans_value = get_transient($trans_key = 'my_transient_key'))) {

    print_r('NO CACHE FOR ' . $trans_key); // (debug output)

    // start the output buffer to capture our generated content

    ob_start();

    // run your expensive operations -- data sent to the screen will be captured

    print_r('This is an expensive operation!');

    // using ob_get_clean we'll store the results and set the value variable.

    // double check the amount of time you want to keep the data cached
    // set to 0 for auto loading on every page hit.

    set_transient($trans_key, $trans_value = ob_get_clean(), 1 * MINUTE_IN_SECONDS);
}
else {
    print_r('THIS IS A CACHED RESULT FOR ' . $trans_key); // (debug output)
}

// value is ready and cached
print_r("<pre>$trans_value</pre>");

To clear the value just delete using the key.

delete_transient ( $trans_key );