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<?php

/**
 * The Events Calendar - Target a Specific Event List Widget to Only Show Today's Events
 *
 *  modify tribe-events-adv-list-widget-2 to id of widget
 */
function tribe_modify_list_widget_args_for_today( $args ) {

	$start_date_init = date ( 'Y-m-d' );
	$start_date_end  = $start_date_init . ' 23:59:59';

	$args['meta_query'][] = array('key' => '_EventStartDate','type' => 'DATETIME','compare' => '>=','value' => $start_date_init);
	$args['meta_query'][] = array('key' => '_EventStartDate','type' => 'DATETIME','compare' => '<=','value' => $start_date_end);

	return $args;

}
add_filter( 'widget_display_callback', 'tribe_target_specific_widget', 10, 2 );
function tribe_target_specific_widget( array $instance, $widget ) {

		remove_filter( 'tribe_events_list_widget_query_args', 'tribe_modify_list_widget_args_for_today', 10, 1 );

	if ( is_a( $widget, 'Tribe__Events__Pro__Advanced_List_Widget' ) &&  $widget->id == 'tribe-events-adv-list-widget-2' ) {

		add_filter( 'tribe_events_list_widget_query_args', 'tribe_modify_list_widget_args_for_today', 10, 1 );

	}

	return $instance;

}