TEC > Community Events > Custom require Event Cost allowing 0 (zero) as value for free events.

functions.php

<?php

/* Custom Event Cost validation */
function tribe_custom_event_cost_validation ( $valid, $submission, $class ) {
	
	/* Prevents submit and adds error message if cost is empty and different than '0' */
	if ( empty( $submission['EventCost'] ) && $submission['EventCost'] != '0' ) {
	
		$valid = false;
		$message = __( '%s is required', 'tribe-events-community' );
		$message = sprintf( $message, 'Event Cost');
		$class->add_message( $message, 'error' );
	
	}

	return $valid;

}

function my_community_add_required_to_fields( $fields ) {

    if ( ! is_array( $fields ) ) {
        return $fields;
    }

    $fields[] = 'EventCost';

    return $fields;
}

function my_community_custom_required_field() {

	add_filter( 'tribe_events_community_required_fields', 'my_community_add_required_to_fields', 10, 1 );

}

add_action( 'tribe_ce_before_event_submission_page_template', 'my_community_custom_required_field', 10, 1 );
add_filter('tribe_community_events_validate_submission', 'tribe_custom_event_cost_validation', 10, 3);