How to order custom posts by one of the custom fields value, 'date'?

Question

I am using this php code to display a list of gigs, which is a custom post type. I want to order it by the 'when' value of the post, and omit the gigs that have already happened. How can I modify the following code to get that happening?

    <?php
$args2 = array(

    'post_type' => 'gig',
    'numberposts' => -1
);
$gigs = get_posts($args2);
foreach ($gigs as $gig){
    echo '<h2>'.$gig->post_title.'</h2><br />';
    // for each custom fields you want.
    echo get_post_meta($gig->ID,'_gigswhen', true).'</br>';
    echo 'Time: '.get_post_meta($gig->ID,'_gigsstart_time', true).'-'.get_post_meta($gig->ID,'_gigsend_time', true).'<br />';
}
?>

TO clarify a bit, here is the code in my functions.php

    $config = array(
        'id' => 'gigs-info',
        'title' => 'Gig Info',
        'pages' => array('gig'),
        'context' => 'normal', 
        'priority' => 'high', 
        'fields' => array(), 
        'local_images' => false,
        'use_with_theme' => true //change path if used with theme set to true, false for a plugin or anything else for a custom path(default false).
    );
    $my_meta = new AT_Meta_Box($config);

    //Add fields to your meta box
    $my_meta->addText($prefix.'where',array('name'=> 'Where is the Gig '));
    $my_meta->addDate($prefix.'when',array('name'=> 'When is the Gig '));
    $my_meta->addTime($prefix.'start_time',array('name'=> 'When Does it Start '));
    $my_meta->addTime($prefix.'end_time',array('name'=> 'When Does it End '));
    $my_meta->addText($prefix.'with_who',array('name'=> 'With Who is the Gig '));
    $my_meta->addTextarea($prefix.'words',array('name'=> 'A few words on the gig '));
    $my_meta->Finish();
}
?>

I'm using a custom meta-box class file that someone kindly pointed me to. So I'm not sure if it's being saved as a unix timestamp or not.. I'm a bit new to wordpress php pogramming :)

Answer 1

After a little research, I'm thinking the ability to "unpublish" or expire a post might be more up your alley. A big part of this is that unless your start_time is in Unix format, WordPress won't really know how to interpret it as something comparable to "now". And I'm assuming you're inserting it into something like a MM/DD/YYYY.

Take a look at some of these plugins, maybe that will get you in the right direction. Hopefully at least one has support for Custom Post Types.

http://wordpress.org/extend/plugins/search.php?q=expire

Answer 2

the best way

If you input the gig time as a unix timestamp (using strtotime()), then you can use WP_Query's meta_value_num in the orderby element to set the order. You can also use WP_Query's meta_query to only get posts that have a date that occur in the future.

the other way

If you can't do this for some reason or another (probably that your date is already set), if you get all the gigs, you can reorder the array of posts based on a strtotime() of your meta value. This will be a heavier implementation performance wise, so go with the other one if possible.