Normally you’d be able to use the custom field parameters in WP_Query, but Piklist doesn’t store the dates in the necessary YYYY-MM-DD format. I’m not sure why. May be worth changing to make this possible!

@Steve: That’s true, and does make sense. Still, it could be useful to store the date in one format and display it in another, as to make date queries possible. Could be a nice extension to the datepicker field.

Hello Angelique,

Why don’t you convert your String date in timestamp with some php functions and store this timestamp as an hidden custom field?

You could afterwards select your CPT on this timestamp custom field with WP_Query.

I did that in one of my project and it works like a charm.
If you need the code, tell me. I can recover it and post it for you.

@kattagami – This code above was a real help. Now that I am able to get the events to list with a little date stamp (see attachment). Is it possible to parse the_date() from the date picker to work in a fashion such as this?

<?php if (true == get_post_meta($the_query->ID, 'mr_evenement_date_timestamp', true) ) { ?>
<p class="date"><?php echo get_post_meta($the_query->ID, 'mr_evenement_date_timestamp', true);?></p>
<?php 

I am trying to get the date to be consisting of just the day number and the month.

Hello Guys, I just remembered that I wrote a complete stable solution just with WordPress action hooks for this that works really well. You can include this in your plugin or theme’s function.php, just replace my field names and post types with yours. This module will insure that your date picker fields will be saved in timestamp format in the database so your plugins will be able to compare dates directly. It will also make sure that this data will be displayed as a clear date format wherever you want to display it, front & admin. Here is the code:

<?php

if( ! defined( 'ABSPATH' ) ) exit; // Exit if accessed directly

/**
 * START PIKLIST DATE PICKER ACTIONS & FILTERS: SAVE AS TIMESTAMP BUT DISPLAY AS DATE IN ADMIN EDIT
 */

// Change the meta data after a post is saved
add_action( 'save_post', 'hdev_update_meta_data' );
function hdev_update_meta_data( $post_id ) {

   // If this is just a revision, don't do anything.
   if ( wp_is_post_revision( $post_id ) )
      return;

   global $post;
   $post_type = $post->post_type;

   /* ******* Change piklist date picker saved date to timestamp format for easy date comparison when needed **** */

   // Make sure any date will be saved in PDT LA Time timestamp format
   date_default_timezone_set('America/Los_Angeles'); /** USE YOUR DESIRED TIMEZONE HERE -- IMPORTANT TO AVOID YOUR DATE FROM BEING CHANGED TO A SLIGHTLY DIFFERENT ONE EACH TIME TIME YOU SAVE YOUR POST */

   if($post_type =='new') // Apply changes only to desired post_types metadata
   {
      $listing_start_date_stamp = strtotime(get_post_meta($post_id, 'YOUR_listing-start-date', true));
      $listing_end_date_stamp = strtotime(get_post_meta($post_id, 'YOUR_listing-end-date', true));
      update_post_meta($post_id, 'YOUR_listing-start-date', $listing_start_date_stamp);
      update_post_meta($post_id, 'YOUR_listing-end-date', $listing_end_date_stamp);
   }
   if(in_array($post_type, array('page', 'post', 'YOUR_OTHER_POST_TYPES_HERE'))) // Apply changes only to desired post_types metadata
   {
      $event_listing_start_date_stamp = strtotime(get_post_meta($post_id, 'YOUR_event-listing-start-date', true));
      $event_listing_end_date_stamp = strtotime(get_post_meta($post_id, 'YOUR_event-listing-end-date', true));
      update_post_meta($post_id, 'YOUR_event-listing-start-date', $event_listing_start_date_stamp);
      update_post_meta($post_id, 'YOUR_event-listing-end-date', $event_listing_end_date_stamp);
   }

   /* *************************************************** */

}

// Change the meta data just when displaying it on the admin edit page but keep it unchanged in the database
add_filter( 'get_post_metadata', 'hdev_convert_timestamp_to_date', 99, 4 );
function hdev_convert_timestamp_to_date($metadata, $object_id, $meta_key, $single){

   if(is_admin() && isset( $meta_key ) && in_array($meta_key, array('YOUR_listing-start-date', 'YOUR_listing-end-date', 'YOUR_event-listing-start-date', 'YOUR_event-listing-end-date')))
   {
      //  Remove this very same filter to avoid infinite loop
      remove_filter( 'get_post_metadata', 'hdev_convert_timestamp_to_date', 99 );
      $meta_value = get_post_meta( $object_id, $meta_key, TRUE );
      add_filter('get_post_metadata', 'hdev_convert_timestamp_to_date', 99, 4);

      // Convert meta value from timestamp to readable (MM d, yy) date format and return it
      if(hdev_is_timestamp($meta_value)) // Check to avoid passing a date to date() instead of a timestamp - case happens during above save_post hook on get_post_meta call while date not converted yet to timestamp...
      {
         return date("F d, Y", $meta_value);
      }
   }

   // Return original if the check does not pass
   return $metadata;

}

/**
 * Checks if a string is a valid timestamp.
 *
 * @param  string $timestamp Timestamp to validate.
 *
 * @return bool
 */
function hdev_is_timestamp($timestamp)
{
   $check = (is_int($timestamp) OR is_float($timestamp))
         ? $timestamp
         : (string) (int) $timestamp;
   return  ($check === $timestamp)
           AND ( (int) $timestamp <=  PHP_INT_MAX)
               AND ( (int) $timestamp >= ~PHP_INT_MAX);
}

/** END PIKLIST DATE PICKER CUSTOM **********************************************/