How to use all tags in post permalinks

To use all tags in a post permalink, try a variation of my similar answer for How to use first tag in permalinks

• add_rewrite_tag( $tag, $regex ) adds a new placeholder you can use in Settings/Permalinks.

• The filter on post_link translates the placeholder into something useful, here a list of all tag slugs, separated by a -.

• Adjust the static variables $default and $placeholder to your needs.

• Then install and activate the code as a plugin, go to Settings/Permalinks and use the new placeholder like this:

  

add_action( 'init', array ( 'T5_All_Tags_Permalink', 'init' ) );

/**
 * Adds '%tag%' as rewrite tag (placeholder) for permalinks.
 */
class T5_All_Tags_Permalink
{
    /**
     * What to use when there is no tag.
     *
     * @var string
     */
    protected static $default="tag";

    /**
     * Used in Settings/Permalinks
     *
     * @var string
     */
    protected static $placeholder="%tags%";

    /**
     * Add tag and register 'post_link' filter.
     *
     * @wp-hook init
     * @return  void
     */
    public static function init()
    {
        add_rewrite_tag( self::$placeholder, '([^/]+)' );
        add_filter( 'post_link', array( __CLASS__, 'filter_post_link' ) , 10, 2 );
    }

    /**
     * Parse post link and replace the placeholder.
     *
     * @wp-hook post_link
     * @param   string $link
     * @param   object $post
     * @return  string
     */
    public static function filter_post_link( $link, $post )
    {
        static $cache = array (); // Don't repeat yourself.

        if ( isset ( $cache[ $post->ID ] ) )
            return $cache[ $post->ID ];

        if ( FALSE === strpos( $link, self::$placeholder ) )
        {
            $cache[ $post->ID ] = $link;
            return $link;
        }

        $tags = get_the_tags( $post->ID );

        if ( ! $tags )
        {
            $cache[ $post->ID ] = str_replace( self::$placeholder, self::$default, $link );
            return $cache[ $post->ID ];
        }

        $slugs = wp_list_pluck( $tags, 'slug' );
        $cache[ $post->ID ] = str_replace( self::$placeholder, join( '-', $slugs ), $link );

        return $cache[ $post->ID ];
    }
}