Order custom posts by a date metabox

Question

I have a custom metabox, where I store the date in plain text like this: dd/mm/yyand now I need to order the posts by that date.The custom field is called event_informations_date

<?php
    $args = array( 'post_type' => 'Event','posts_per_page' => 1000 );
    $loop = new WP_Query( $args );
?>
<?php while ( $loop->have_posts() ) : $loop->the_post(); ?>

Answer 1

When you're saving the data on your custom post type you need to set it so that the meta box value is actually stored as a UNIX timestamp, eg:

if(!isset($_POST["event_informations_date"])) {
    return $post;
} else {
    $event_as_timestamp = strtotime ( $_POST["event_informations_date"];
    update_post_meta($post->ID, "event_informations_date", $event_as_timestamp );
}

This way you will have an orderable value for your meta keys. And you can query as per @helgatheviking

$args = array( 'post_type' => 'Event',
           'posts_per_page' => 1000,
           'order_by' => 'meta_value_num',
            'meta_value' => 'event_informations_date'  );

You will need to make sure that the add_meta_box() function you're using converts the UNIX timestamp from saved custom field values back to the format you need.

Answer 2

first you'll need to add more parameters

$args = array( 'post_type' => 'Event',
               'posts_per_page' => 1000,
               'order_by' => 'meta_value_num',
                'meta_value' => 'event_informations_date'  );

the problem will be that you can't really sort by your string date. i'd use 'meta_value' but b/c you have dd/mm/yy you're basically looking at all events on the first of the month being grouped together followed by those that start with 2, etc. i think you'll need to change the way your date is stored so that you'll be able to sort by it. maybe a unix timestamp?

ps- if you want all posts, i think you should change posts_per_page to -1