Sorting meta box values by start- and enddate and all dates in between

Question

What I've been attempting to write is a function that will allow me to sort a list of WordPress posts by their meta values start date, end date and all dates in between.

I've set up a custom metabox with three fields:

• Name of the event (ID evenement-name)
• Start date of event (ID evenement-datum-start), stored as YY-mm-dd
• End date of the event (ID evenement-datum-end), stored as YY-mm-dd

What I'd like to have is a list of events that would take place in the future, grouped by year, month and day.

Example:

• Event A takes place from 2013/11/24 till 2013/11/26
• Event B takes place on 2013/11/25

Example result:

2013

November

24

Event A

25

Event A

Event B

26

Event A

Unfortunately, that all sounds so much easier in theory.

I did manage to get the metaboxes working and run query to return a list of posts of which the meta value evenement-datum-end is today or in the future. I even managed to get a list of all dates between evenement-datum-start and evenement-datum-end, so what I now have is this:

2013/11/24 - Event A

2013/11/25 - Event A

2013/11/26 - Event A

2013/11/25 - Event B

My code:

//This is the function I use to get all the dates between the start date and the end date:
function getDateRange($startDate, $endDate, $format="Y-m-d"){
    //Create output variable
    $datesArray = array();
    //Calculate number of days in the range
    $total_days = round(abs(strtotime($endDate) - strtotime($startDate)) / 86400, 0) + 1;

    //Populate array of weekdays and counts
    for($day=0; $day<$total_days; $day++)
    {
        $datesArray[] = date($format, strtotime("{$startDate} + {$day} days"));
    }
    //Return results array: de inhoud van de array wordt uitgelezen 
    return $datesArray;
}


//Query
$args = array ( 
    'cat'               => '1,6',
    'post_type'         => 'post', 
    'meta_key'          => 'evenement-datum-start',
    'posts_per_page'    => -1,
    'meta_query'        => array(
        array(
            'key'       => 'evenement-datum-end',
            'value'     => date('Y-m-d'),
            'compare'   => '>=',
            'type'      => 'DATE'
        )
    ),
 );

$agenda_query_full = new WP_Query ( $args );


if ( $agenda_query_full->have_posts() ) {
echo '<ul>';

    while ( $agenda_query_full->have_posts() ) {
        $agenda_query_full->the_post();

        $meta_event_name    = get_post_meta( get_the_ID(), 'evenement-name', true );
        $meta_event_start   = get_post_meta( get_the_ID(), 'evenement-datum-start', true );
        $meta_event_end     = get_post_meta( get_the_ID(), 'evenement-datum-end', true );
        $dateRange      = getDateRange($meta_event_start, $meta_event_end); 

        asort($dateRange);
        $today              = date('Y-m-d');

        foreach ($dateRange as $key => $val) {
            $datum      = date("d-m-Y", strtotime($val));   

            if($val>=$today) {

                if(in_category( 'acties' ) ){
                    echo '<li>'.$datum.' - <a href="' . get_page_link() . '">' . $meta_event_name . '</a></li>';
                }
                else {
                    echo '<li>'.$datum.' - ' . $meta_event_name . '</li>';
                };
            };
        }
    }
    echo '</ul>';
} else {
    echo 'No events found.';
}

wp_reset_postdata();

As I understand it, and I'm only a beginner at PHP, is that I can't query for a list of dates before I run the loop. But when I do run the loop, I can't get the dates to be sorted chronologically, because I've already retrieved a single post. Impasse reached.

I've been working on this for several days now and getting desperate... Any help?

Answer 1

I think you can do the trick running 2 loops, in the first you prepare an helper array of posts ordered by date, in the second you display this array:

Something like this (completely untested):

if ( $agenda_query_full->have_posts() ) {
  $date_events = array(); // helper array
  $today = date('Y-m-d');
  while ( $agenda_query_full->have_posts() ) {
    $agenda_query_full->the_post();
    global $post;
    $metas = get_post_custom();
    // save event name in the post object
    $post->ename = array_pop( $metas['evenement-name'] ); 
    $meta_event_start = array_pop( $metas['evenement-datum-start'] );
    $meta_event_end = array_pop( $metas['evenement-datum-end'] );
    $dateRange = getDateRange( $meta_event_start, $meta_event_end ); 
    asort($dateRange);
    foreach ( $dateRange as $date ) {
      if( $date < $today ) continue; // skip past events
      if ( ! isset($date_events[$date]) ) $date_events[$date] = array();
      $date_events[$date][] = $post; // put post in helper array that is keyed by date
    }
  }
  if ( ! empty($date_events) ) {
    foreach ( $date_events as $date => $events ) {
      $datum = date( "d-m-Y", strtotime($date) );
      echo '<h3>' . $datum . '</h3>';
      echo '<ul>'; 
      foreach ( $events as $event ) {
        if( in_category( 'acties', $event ) ){
        echo '<li><a href="' . get_page_link( $event->ID ) . '">' . $event->ename . '</a></li>';
        } else {
        echo '<li>' . $event->ename . '</li>';
        };
      }
      echo '</ul>';
    }
  } else {
    echo 'No events found.';
  }
} else {
    echo 'No events found.';
}
wp_reset_postdata();