Meta Date Archive

version: 1.2
Tested up to: 4.2.2

This plugin replaces the default date archives with archives for posts that have a start and end date custom field. Or use it to query for posts between two date custom fields.

Enable the custom fields archive and add a start and end date custom field to your posts for them to show up in the date archives.

Note: If you only provide one of the date custom field when saving a post the plugin automatically saves the other date custom field with the same date.

It finds posts with overlapping start and end dates. For example if you're on a date archive for the month of may (example.com/2015/05) it displays posts that have the custom field values:

• start date in may and end date in may.
• start date in may and end date after may.
• start date before may and end date in may.
• start date before may and end date after may.

The format for the start and end date custom field values is YYYYMMDD (Year Month Day). Example 20150521.

Registering custom field keys

The start and end date custom field keys are by default meta_start_date and meta_end_date.

To register your own start and end date custom field keys use this in your (child) theme's functions.php file.

add_filter( 'meta_date_archive_start', 'meta_date_archive_start_key' );
add_filter( 'meta_date_archive_end',   'meta_date_archive_end_key' );

function meta_date_archive_start_key( $key ) {
   // Return your custom field start date key
   return 'start_date';
}

function meta_date_archive_end_key( $key ) {
   // Return your custom field end date key
   return 'end_date';
}

Enable the custom fields archive.

The custom fields archive is not enabled by default. Put this in your (child) theme's functions.php file to enable it.

add_filter( 'meta_date_archives', '__return_true' );

Or enable it from the pre_get_posts action.

function enable_custom_field_archive( $query ) {

	if ( !is_admin() && $query->is_main_query() ) {

		if ( is_date() ) {
			// date archives
			$query->set( 'meta_date_archives', 1 );

			// set your own query vars here
			$query->set( 'meta_key', 'end_date' ); // your end date meta key
			$query->set( 'orderby',  'meta_value' ); // meta_value or meta_value_num
			$query->set( 'order',    'ASC' ); // ASC or DESC			
		}
	}
}

add_action( 'pre_get_posts', 'enable_custom_field_archive' );

Custom Queries

Use the query variables meta_archive_start_date and meta_archive_end_date for the start and end dates. If you provide only one of the two the plugin assumes both start and end dates are the same.

Example:

<?php
$args = array (
	'meta_archive_start_date' => '20150601',
	'meta_archive_end_date'   => '20150630',

	// set your own query vars here
	'post_type'      => 'post',
	'posts_per_page' => 10,
	'meta_key'       => 'end_date', // your end date meta key
	'orderby'        => 'meta_value', // meta_value or meta_value_num
	'order'          => 'ASC', // ASC or DESC
);

$date_query = new WP_Query( $args );
?>

Calendar Example

This example shows how you would show your dates in a calender using the SimpleCalendar class

Step one

Include the SimpleCalendar.php and SimpleCalendar.css in your theme.

Step two

Put this in the theme template where you want to show the calendar. In this example the custom field keys are start_date and end_date

This example shows the calendar for the current month

<?php
$date_obj = new DateTime();

$args = array (
	'meta_archive_start_date' => $date_obj->format( 'Ym01' ), // first day of current month
	'meta_archive_end_date'   => $date_obj->format( 'Ymt' ), // last day of current month
	'posts_per_page'          => -1, // show all posts in the calendar
	
	// set your own query vars here
	'post_type'      => 'post',
	'meta_key'       => 'end_date', // your end date meta key
	'orderby'        => 'meta_value', // meta_value or meta_value_num
	'order'          => 'ASC', // ASC or DESC
);

$date_posts = get_posts( $args );

if ( $date_posts ) {

	// Use the current year and month to instantiate
	$calendar = new donatj\SimpleCalendar( $date_obj->format( 'Y-m' ) );

	// Set the start of the week.
	$calendar->setStartOfWeek( 'Sunday' );

	foreach ( $date_posts as $post ) {

		// Get the dates.
		$start = get_post_meta( $post->ID, 'start_date', true );
		$end   = get_post_meta( $post->ID, 'end_date', true );

		// Add the dates to the calendar.
		$calendar->addDailyHtml( $post->post_title, $start, $end );
	}

	// Show the calendar.
	$calendar->show( true );
}
?>