adding custom event attribute in search

Hy,

I would like to add another search field.
With event attributes

Found this guide
https://www.beetlebrow.co.uk/about-us/beetle-blog/wordpress-event-manager-plugin-adding-custom-event-attribute

I think the variable or the code is outdated.
Since no results will be given.

Can anyone read times about the code, which is possibly wrong?
Gladly a cafe donation for the finder,)

Many Thanks

<?php

 // START EM Custm Attribute "Teacher" search
 /* Create a new search attribute form entry for our new Event Attribute "teacher" (#_ATT{teacher})
 The values are hard-coded but could probably be automatically selected
 Add this field to the search form using an EM action.
 nb. The action doc'd here https://wp-events-plugin.com/tutorials/adding-custom-event-search-form-fields/
 does not seem to exist so use the footer one for inclusion in advanced search or the header one
 for normal search. Read the source Luke.
 */
 function my_teacher_search_field(){ ?>
 <div class="em-search-teacher em-search-field">
 <label>Test</label>
 <select name="teacher">
 <option value=''>Alle</option>
 <option value="Abi" <?php echo ((array_key_exists('teacher', $_POST)) && $_POST['teacher'] == "Abi") ? 'selected="selected"':''; ?>>Open</option>
 <option value="Lou" <?php echo ((array_key_exists('teacher', $_POST)) && $_POST['teacher'] == "Lou") ? 'selected="selected"':''; ?>>close</option>
 </select>
 </div>
 <?php }
 add_action('em_template_events_search_form_footer', 'my_teacher_search_field');
 //
 /* Hook the new search attribute teacher into default search filter,
 so it isn’t ignored when Events Manager creates an events search query
 */
 function my_teacher_search($searches, $array){
 if( !empty($array['teacher']) ){
 $searches['teacher'] = $array['teacher'];
 }
 return $searches;
 }
 add_filter('em_events_get_default_search','my_teacher_search',1,2);

 /* This isn't needed. It seems that inclusion in the default_search filter
 is all thats needed. See https://wp-events-plugin.com/tutorials/adding-custom-event-search-form-fields
 */
 //function my_teacher_accepted_searches($searches){
 // $searches[] = 'teacher';
 // return $searches;
 //}
 //add_filter('em_accepted_searches','my_teacher_accepted_searches',1,1);

 /* Can't hook into em_events_get filter as doc'd here
 https://wp-events-plugin.com/tutorials/creating-custom-event-search-attributes/
 as we need to join with kal_postmeta and not just filter kal_em_events
 so append a subquery via sql_conditions hook to find kal_postmeta using our new search attribute and return valid
 posts ids for main event query that is internally appended to display.
 */
 function my_teacher_conditions($conditions, $args){
 if( !empty($args['teacher'])) {
 $teacherval = $args['teacher'];
 $conditions['teacher'] = " (kal_em_events.post_id IN ( SELECT post_id FROM kal_postmeta WHERE (kal_postmeta.meta_key = 'teacher' AND kal_postmeta.meta_value = '$teacherval')))";
 }
 return $conditions;
 }
 add_filter( 'em_events_build_sql_conditions', 'my_teacher_conditions',1,2);
 //
 // END EM Custom Attribute Teacher Search

?>