Questions

// The initial set-up requires initialising two post types, questions and answers,
// also managing capabilities for these.
function register_question_post_types() {

    register_post_type(
        'question',
        array(
            'label' => 'Questions',
            'labels' => array(
                'name' => 'Questions',
                'singular_name' => 'Question',
                'edit_item' => 'Edit Question',
                'view_item' => 'View Question'
            ),
            'exclude_from_search' => false,
            'publicly_queryable' => true,
            'show_ui' => true,
            'capability_type' => 'question',
            'capabilites' => array(
                'publish_posts' => 'publish_questions',
                'edit_posts' => 'edit_questions',
                'edit_others_posts' => 'edit_others_questions',
                'delete_posts' => 'delete_questions',
                'delete_others_posts' => 'delete_others_questions',
                'read_private_posts' => 'read_private_questions',
                'edit_post' => 'edit_question',
                'delete_post' => 'delete_question',
                'read_post' => 'read_question',
            ),
            'supports' => array( 'title', 'editor', 'author', 'excerpt', 'comments', 'revisions' ),
            'has_archive' => true
        )
    );

    register_post_type(
        'answer',
        array(
            'label' => 'Answers',
            'labels' => array(
                'name' => 'Answers',
                'singular_name' => 'Answer',
                'edit_item' => 'Edit Answer',
                'view_item' => 'View Question'
            ),
            'exclude_from_search' => false,
            'publicly_queryable' => false,
            'show_ui' => true,
            'show_in_menu' => 'edit.php?post_type=question', // Display within the "Questions" menu
            'capability_type' => 'answer',
            'capabilites' => array(
                'publish_posts' => 'publish_answers',
                'edit_posts' => 'edit_answers',
                'edit_others_posts' => 'edit_others_answers',
                'delete_posts' => 'delete_answers',
                'delete_others_posts' => 'delete_others_answers',
                'read_private_posts' => 'read_private_answers',
                'edit_post' => 'edit_answer',
                'delete_post' => 'delete_answer',
                'read_post' => 'read_answer',
            ),
            'supports' => array( 'title', 'editor', 'author', 'comments', 'revisions' )
        )
    );

    add_filter( 'map_meta_cap', 'questions_map_meta_cap', 10, 4 );
    add_filter( 'map_meta_cap', 'answers_map_meta_cap', 10, 4 );

    // Mapping the meta capabilities so that users can edit their own questions/answers, publish
    // them, delete them, etc. Borrowed from Justin Tadlock:
    // [ http://justintadlock.com/archives/2010/07/10/meta-capabilities-for-custom-post-types ]
    function questions_map_meta_cap( $caps, $cap, $user_id, $args ) {

        /* If editing, deleting, or reading a question, get the post and post type object. */
        if ( 'edit_question' == $cap || 'delete_question' == $cap || 'read_question' == $cap ) {
            $post = get_post( $args[0] );
            $post_type = get_post_type_object( $post->post_type );

            /* Set an empty array for the caps. */
            $caps = array();
        }

        /* If editing a question, assign the required capability. */
        if ( 'edit_question' == $cap ) {
            if ( $user_id == $post->post_author )
                $caps[] = $post_type->cap->edit_posts;
            else
                $caps[] = $post_type->cap->edit_others_posts;
        }

        /* If deleting a question, assign the required capability. */
        elseif ( 'delete_question' == $cap ) {
            if ( $user_id == $post->post_author )
                $caps[] = $post_type->cap->delete_posts;
            else
                $caps[] = $post_type->cap->delete_others_posts;
        }

        /* If reading a private question, assign the required capability. */
        elseif ( 'read_question' == $cap ) {

            if ( 'private' != $post->post_status )
                $caps[] = 'read';
            elseif ( $user_id == $post->post_author )
                $caps[] = 'read';
            else
                $caps[] = $post_type->cap->read_private_posts;
        }

        /* Return the capabilities required by the user. */
        return $caps;
    }

    // Do it all again for answers
    function answers_map_meta_cap( $caps, $cap, $user_id, $args ) {

        /* If editing, deleting, or reading a answer, get the post and post type object. */
        if ( 'edit_answer' == $cap || 'delete_answer' == $cap || 'read_answer' == $cap ) {
            $post = get_post( $args[0] );
            $post_type = get_post_type_object( $post->post_type );

            /* Set an empty array for the caps. */
            $caps = array();
        }

        /* If editing a answer, assign the required capability. */
        if ( 'edit_answer' == $cap ) {
            if ( $user_id == $post->post_author )
                $caps[] = $post_type->cap->edit_posts;
            else
                $caps[] = $post_type->cap->edit_others_posts;
        }

        /* If deleting a answer, assign the required capability. */
        elseif ( 'delete_answer' == $cap ) {
            if ( $user_id == $post->post_author )
                $caps[] = $post_type->cap->delete_posts;
            else
                $caps[] = $post_type->cap->delete_others_posts;
        }

        /* If reading a private answer, assign the required capability. */
        elseif ( 'read_answer' == $cap ) {

            if ( 'private' != $post->post_status )
                $caps[] = 'read';
            elseif ( $user_id == $post->post_author )
                $caps[] = 'read';
            else
                $caps[] = $post_type->cap->read_private_posts;
        }

        /* Return the capabilities required by the user. */
        return $caps;
    }

}

// Run all that at init
add_action( 'init', 'register_question_post_types' );

?>