How to add custom columns to Custom Post Type admin screen

Question

I have another dumb question, but I can't get one thing :)

I've found this very good article on creating custom post types:

http://thinkvitamin.com/code/create-your-first-wordpress-custom-post-type/

I'm not sure how Step 4 works.

This guys writes:

add_action("manage_posts_custom_column",  "portfolio_custom_columns");
add_filter("manage_edit-portfolio_columns", "portfolio_edit_columns");

function portfolio_edit_columns($columns){
  $columns = array(
    "cb" => "<input type=\"checkbox\" />",
    "title" => "Portfolio Title",
    "description" => "Description",
    "year" => "Year Completed",
    "skills" => "Skills",
  );

  return $columns;
}
function portfolio_custom_columns($column){
  global $post;

  switch ($column) {
    case "description":
      the_excerpt();
      break;
    case "year":
      $custom = get_post_custom();
      echo $custom["year_completed"][0];
      break;
    case "skills":
      echo get_the_term_list($post->ID, 'Skills', '', ', ','');
      break;
  }
}

I have two different post types ('books' and 'movies').

And I can't get how to link this code with right one!

I'm sure I'm missing something (most likely in the code), but I didn't see him including "portfolio_edit_columns" anywhere in the code.

I have found this in WP Codex: http://codex.wordpress.org/Plugin_API/Action_Reference/manage_posts_custom_column and it seems like

manage_edit-${post_type}_columns

does the magic, but I've tried both manage_edit-books_columns and manage_edit-movies_columns and nothing! :)

So how to create two separate column layouts for different post types?

Answer 1

The code from ThinkVitamin is right. I think the problem came from else where in your code.

Actually, the hook manage_edit-${post_type}_columns takes an argument $columns which is an array of all registered columns. To add a new column, just add a new element to this array, like this:

add_filter('manage_edit-film_columns', 'my_columns');
function my_columns($columns) {
    $columns['views'] = 'Views';
    return $columns;
}

Answer 2

It´s even easier than you belive.

You have this two functions on wp:

manage_posts_columns (notice the "posts" part)

and

manage_posts_custom_column (again "posts")

You have same thing for pages, "manage_page_posts_columns" and "manage_page_posts_custom_column" (notice the "page_posts" part)

So, if you need to add those cols for x post type, you only need to do like this, le´t say your custom post type name is "movie", then:

manage_movie_posts_columns()
manage_movie_posts_custom_column()

Notice the "movie_posts" part, that´s why you see something like "manage_{custom_type}_posts_columns" on codex pages.

For a "books" custom type:

manage_books_posts_columns()
manage_books_posts_custom_column()

And so on... got it?

Answer 3

Take a look at how the rewrite $arg for your custom post type is.

To get a better view of the output data, just do something like

echo '<pre>';   
print_r($custom_post_type_obj);   
echo '</pre>';   

on the post type object when querying it.