How can I return shortcode output to the top of the content?

Question

I have a shortcode called update which is used as follows

[update title='' date=''] this is some update, etc. etc. 2 paragraphs or more [/update]

This outputs some html that wrap the title, date and content in some html.

Along wit this, I would like spit out a single line at the top of the content that outputs just the title and date with an anchor that jumps to the point where the update was created.

I've looked high and low, but I cant seem to find a way to position the shortcode just above the content.

Any help appreciated!

Thank you

Answer 1

A cleaner way than my first suggestion would be this:

• Run the shortcode handler two times: 1. before the content is parsed, 2. during the regular content parsing.
• Store the data you want to prepend in a variable.

It is important to use 'the_post' as first entry. Otherwise you can get strange side effect in cases where a widget or some other code uses the_content filters.

add_shortcode( 'test',  array ( 'WPSE_77804_Shortcode', 'shortcode_handler' ) );
add_action( 'the_post', array ( 'WPSE_77804_Shortcode', 'store_output' ) );

class WPSE_77804_Shortcode
{
    protected static $storage = '';

    public static function store_output( $post )
    {

        // maybe someone else has done this already, so we don't have to try again.
        '' === self::$storage && do_shortcode( $post->post_content );

        '' !== self::$storage
            && add_filter( 'the_content', array ( __CLASS__, 'prepend_content' ) );
    }

    public static function shortcode_handler( $attrs, $content = '' )
    {
        if ( '' === self::$storage )
        {
            if ( isset ( $attrs['title'] ) )
                self::$storage .= $attrs['title'];

            if ( isset ( $attrs['date'] ) )
                self::$storage .= ' ' . $attrs['date'];
        }

        // you might do much more here and return the complete string
        return '|' . self::$storage . '|' . $content;
    }

    public static function prepend_content( $content )
    {
        return self::$storage . '<hr>' . $content;
    }
}

Related answer for galleries.

Answer 2

It sounds like the way to handle this is to use a global array in your theme's functions.php, and add to it whenever one of these shortcodes is processed. Finally, a filter on the_content can be used to place the extra links at the top.

Start by initializing the global:

add_action( 'after_setup_theme', 'update_init' );
function update_init() {
    global $update_links;
    $update_links = array();
}

Then add the following code to your shortcode processing function:

global $update_links;
$update_links[] = "<a href='#$title-$date'>$title - $date</a>";

The above also assumes that your shortcode replacement includes an anchor tag of $title-$date.

Finally, add a content filter to add the update links to your content:

add_filter( 'the_content', 'the_content_update_links', 90);    
function the_content_update_links($content) {
    global $update_links;
    if(count($update_links)) $content = implode("<br />", $update_links).$content;
    return $output;
}

You can change the way the links are put together - I just put a break between them but it would be simple to loop through and create an unordered list or wrap the links in a div.

Answer 3

You can catch your shortcode before its "time for shortcodes" using the_content filter hook and return it before the rest of the content:

add_filter('the_content','update_shortcode_catch',10);
function update_shortcode_catch($content){
    //early exit if not found
    if (strpos($content, '[update') === false)
        return $content;

    //extract shortcode (could use regex)
    $shortcode_start = explode('[update', $content);
    $shortcode_end = explode('[/update]', $shortcode_start[1]);
    $shortcode = '[update' . $shortcode_end[0] . '[/update]';

    //render the update shortcode
    $update = do_shortcode($shortcode);

    //remove the shortcode from te content
    $content = str_replace($shortcode, "", $content);

    //then return the update before the content
    return $update.$content;

}