Create listing with multiple categories on front-end

[lehner_andreas]

Ah I think this solves it.

@sabine

add_filter(
	'hivepress/v1/forms/listing_submit',
	function( $form ) {
		if(isset($form['fields']['categories'])){
			$form['fields']['categories']['multiple'] = true;	
		}
		return $form;
	},
	1000
);

How can I use this for vendors as well?