Custom Post Types and Better Permalinks

I just found a really nifty new trick for using more flexible permalinks for custom post types in WordPress (v3.0 and later). A bit of a back story here:

At a recent DC PHP beverage subgroup I mentioned to Andrew Nacin (@nacin) that I didn’t know anything about WP_Rewrite (the WordPress API that handles permalinks); he said ‘Good luck with that!’ and I felt obligated to learn it. Later, Aaron Jorbin (@aaronjorbin) made the same challenge.

So I opened my phpxref of WordPress and just sat down with the code, and knew it very well ten hours later. I even understand what the EP Masks do. It’s pretty cool stuff, but not for the faint of heart. (see more beneath the fold)

So recently, I made a “News Releases” custom post type on a site. The default permalink for custom post types is http://www.example.com/post_type/post_name/. For a news feed, I wanted to make the permalinks look a little bit more like blog posts, but with ‘newsroom’ before (i.e.: http://www.example.com/newsroom/year/month/post_name/). So here’s how I did it:

First, in the custom post type registration function, turn rewrite OFF:

register_post_type( 'news', array(
  'rewrite' => false,
  'public' => true
) );

Next, add a rewrite tag, permastruct, and rewrite rule to handle all the rewriting we could need:

add_rewrite_tag( '%news%', '([^/]+)' );
add_permastruct( 'news', '/newsroom/%year%/%monthnum%/%news%/', true, 1 );
add_rewrite_rule( 'newsroom/?$', 'index.php?post_type=news', 'top' );

This is the meat of the rewriting. I won’t go into the details of how or why this works, since it’s very complex. But it does. I may go into how rewrite works at a later date, but right now I want to share just the snippet.

This is almost the end. All of the previous code gets hooked into init. The next part completes the permalinking:

function jpb_cp_news_permalink( $link, $post, $leavename, $sample ){
  if( 'news' != $post->post_type )
    return $link;
  $rewritecode = array(
    '%year%',
    '%monthnum%',
    '%day%',
    '%hour%',
    '%minute%',
    '%second%',
    $leavename? '' : '%postname%',
    '%post_id%',
    $leavename? '' : '%pagename%',
    $leavename? '' : '%news%',
  );
  $unixtime = strtotime($post->post_date);
  $date = explode(' ', date('Y m d H i s', $unixtime));
  $replace_array = array(
    $date[0],
    $date[1],
    $date[2],
    $date[3],
    $date[4],
    $date[5],
    $post->post_name,
    $post->ID,
    $post->post_name,
    $post->post_name,
  );
  $path = str_replace($rewritecode, $replace_array, $link);
  return $path;
}

This function runs any time you pull a ‘news’ post type permalink and adds the correct information. This will even get you the correct permalink with editable slug on the post edit page. This function hooks into post_type_link. So all together now:

function jpb_cp_custom_permalinks(){
  register_post_type( 'news', array(
    'rewrite' => false,
    'public' => true
  ) );

  add_rewrite_tag( '%news%', '([^/]+)' );
  add_permastruct( 'news', '/newsroom/%year%/%monthnum%/%news%/', true, 1 );
  add_rewrite_rule( 'newsroom/?$', 'index.php?post_type=news', 'top' );
}

add_action( 'init', 'jpb_cp_custom_permalinks' );

function jpb_cp_news_permalink( $link, $post, $leavename, $sample ){
  if( 'news' != $post->post_type )
  return $link;
  $rewritecode = array(
    '%year%',
    '%monthnum%',
    '%day%',
    '%hour%',
    '%minute%',
    '%second%',
    $leavename? '' : '%postname%',
    '%post_id%',
    $leavename? '' : '%pagename%',
    $leavename? '' : '%news%',
  );
  $unixtime = strtotime($post->post_date);
  $date = explode(' ', date('Y m d H i s', $unixtime));
  $replace_array = array(
    $date[0],
    $date[1],
    $date[2],
    $date[3],
    $date[4],
    $date[5],
    $post->post_name,
    $post->ID,
    $post->post_name,
    $post->post_name,
  );
  $path = str_replace($rewritecode, $replace_array, $link);
  return $path;
}

add_action( 'post_type_link', 'jpb_cp_news_permalink', 10, 4 );

And now you’ve got a custom post type that looks and acts exactly like a blog post!

One final note: after implementing this code, you will have to refresh your permalink settings. To do so, go to Settings -> Permalinks and hit save (you don’t even need to change anything).

EDIT
————————-
So I found a couple of areas where the code I posted could be improved. Namely, the fact that the permalink didn’t create archives of content. Here’s the modified code:

function jpb_cp_custom_permalinks(){
  register_post_type( 'news', array(
    'rewrite' => array('slug'=>'newsroom'),
    'public' => true
  ) );
  add_rewrite_tag( '%news%', '([^/]+)' );
  $extra_post_types = get_post_types( array( '_builtin' => false, 'publicly_queryable' => true ) );
  if( empty( $extra_post_types ) )
    return;
  add_rewrite_tag( '%post_type%', '('.implode('|',$extra_post_types).')' );
  add_permastruct( 'news', '/%post_type%/%year%/%monthnum%/%news%/', true, 1 );
}

add_action( 'init', 'jpb_cp_custom_permalinks' );

function jpb_cp_news_permalink( $link, $post, $leavename, $sample ){
  if( 'news' != $post->post_type )
    return $link;
  $rewritecode = array(
    '%year%',
    '%monthnum%',
    '%day%',
    '%hour%',
    '%minute%',
    '%second%',
    $leavename? '' : '%postname%',
    '%post_id%',
    '%post_type%',
    $leavename? '' : '%pagename%',
    $leavename? '' : '%news%',
  );
  $unixtime = strtotime($post->post_date);
  $date = explode(' ', date('Y m d H i s', $unixtime));
  $replace_array = array(
    $date[0],
    $date[1],
    $date[2],
    $date[3],
    $date[4],
    $date[5],
    $post->post_name,
    $post->ID,
    $post->post_type,
    $post->post_name,
    $post->post_name,
  );
  $path = str_replace($rewritecode, $replace_array, $link);
  return $path;
}

add_action( 'post_type_link', 'jpb_cp_news_permalink', 10, 4 );

Note that I am using the rewrite attribute of the post type now. Also, the call to add_rewrite_rule has been removed now that we have a rewrite tag to replace it (%post_type%).