Temp workaround: require that a new or existing venue is submitted via the CE frontend submission form

temp-workaround-76297.php

<?php
/**
 * Require that a new or existing venue is specified when events are submitted via
 * the frontend submission form provided by Community Events.
 *
 * This is a temporary workaround for bug #76297.
 */

function ce_submissions_require_venue( array $submission ) {
	// Unhook self
	remove_filter( 'tribe_events_community_sanitize_submission', 'ce_submissions_require_venue' );

	// Gather submitted venue data
	$venue_ids  = (array) Tribe__Utils__Array::get( $submission, array( 'Venue', 'VenueID' ), array() );
	$new_venues = (array) Tribe__Utils__Array::get( $submission, array( 'Venue', 'Venue' ), array() );

	// If there are signs of valid existing venues being specified, do nothing more
	foreach ( $venue_ids as $possible_id ){
		if ( absint( $possible_id ) ) {
			return $submission;
		}
	}

	// If there are signs of new venues being submitted, do nothing more
	foreach ( $new_venues as $venue_name ) {
		$venue_name = trim( $venue_name );

		if ( ! empty( $venue_name ) ) {
			return $submission;
		}
	}

	// Force the venue check to run and fail
	add_filter( 'tribe_events_community_required_fields', 'ce_submissions_add_venue_check' );
	add_filter( 'tribe_events_community_required_venue_fields', 'ce_submissions_add_failure_field' );
	add_filter( 'tribe_community_events_form_errors', 'ce_submissions_tidy_venue_error_message' );
	return $submission;
}

function ce_submissions_add_venue_check( array $required_fields ) {
	$required_fields[] = 'venue';
	return $required_fields;
}

function ce_submissions_add_failure_field( array $required_fields ) {
	$required_fields[] = '__unfindable';
	return $required_fields;
}

function ce_submissions_tidy_venue_error_message( array $errors ) {
	foreach ( $errors as $index => $error_message ) {
		$message = $error_message['message'];

		if ( false !== strpos( $message, '__unfindable' ) ) {
			$errors[ $index ]['message'] = ce_submissions_strip_unfindable_error( $message );
		}
	}

	return $errors;
}

function ce_submissions_strip_unfindable_error( $message ) {
	$fragments = explode( '</p>', $message );

	foreach ( $fragments as $index => $single_message ) {
		if ( false !== strpos( $single_message, '__unfindable' ) ) {
			unset( $fragments[ $index ] );
		}
	}

	return join( '</p>', $fragments );
}

add_filter( 'tribe_events_community_sanitize_submission', 'ce_submissions_require_venue' );