Filtering custom post types by an ACF field.

filter.md

Filtering posts via an ACF field.

• Define the acf key
• grab the choices
• create a select with choices
• request on the meta key/meta value

functions.php

function my_restrict_manage_posts() {
    global $typenow;

    if ($typenow == 'adtrak_applicants'){
        $field_key = "field_553fafc094dc6";
        $field = get_field_object($field_key)['choices'];

        ?>
        <select name="adtrak_applicants_filter">
        <option value=""><?php _e('All statuses', 'adtrak_applicants'); ?></option>
        <?php
            $current_v = isset($_GET['adtrak_applicants_filter']) ? $_GET['adtrak_applicants_filter'] : '';
            foreach ($field as $label => $value) {
                printf (
                    '<option value="%s"%s>%s</option>',
                    $value,
                    $value == $current_v? ' selected="selected"':'',
                    $label
                );
            }
        ?>
        </select>
        <?php
    }
}
add_action('restrict_manage_posts','my_restrict_manage_posts');

function request_applicant_filter($request) {    
    if (is_admin() && isset($request['post_type']) && $request['post_type']=='adtrak_applicants') {
        $request['meta_key'] = 'status';
        $request['meta_value'] = $_GET['adtrak_applicants_filter'];
    }
    return $request;
}
add_action( 'request', 'request_applicant_filter' );