Title: Dynamic Population fields cause error Last modified: May 18, 2023 --- # Dynamic Population fields cause error * Resolved [Robertmurdock](https://wordpress.org/support/users/robertmurdock153/) * (@robertmurdock153) * [3 years ago](https://wordpress.org/support/topic/dynamic-population-fields-cause-error/) * Hello, * We are using the country and state fields in the default registration form. We have added the call-back function as per the document guide. * [https://docs.ultimatemember.com/article/1486-how-to-use-choices-callback](https://docs.ultimatemember.com/article/1486-how-to-use-choices-callback) * When we register the new user we are facing the below error. * 173.239.214.73:0] PHP Fatal error: Uncaught TypeError: rtrim(): Argument #1 ( $string) must be of type string, array given in /nas/content/live/testwebiste/ wp-content/plugins/ultimate-member/includes/core/class-fields.php:3321\nStack trace:\n#0 /nas/content/live/testwebiste/wp-content/plugins/ultimate-member/includes/ core/class-fields.php(3321): rtrim(Array)\n#1 /nas/content/live/testwebiste/wp- content/plugins/ultimate-member/includes/core/class-fields.php(4191): um\core\ Fields->edit_field(‘state_today’, Array)\n#2 /nas/content/live/testwebiste/wp- content/plugins/ultimate-member/includes/core/um-actions-register.php(626): um\ core\Fields->display(‘register’, Array)\n#3 /nas/content/live/testwebiste/wp- includes/class-wp-hook.php(308): um_add_register_fields(Array)\n#4 /nas/content/ live/testwebiste/wp-includes/class-wp-hook.php(332): WP_Hook->apply_filters(”, Array)\n#5 /nas/content/live/testwebiste/wp-includes/plugin.php(517): WP_Hook- >do_action(Array)\n#6 /nas/content/live/testwebiste/wp-content/plugins/ultimate- member/templates/register.php(75): do_action(‘um_main_registe…’, Array)\n#7 / nas/content/live/testwebiste/wp-content/plugins/ultimate-member/includes/core/ class-shortcodes.php(290): include(‘/nas/content/li…’)\n#8 /nas/content/live/ testwebiste/wp-content/plugins/ultimate-member/includes/core/class-shortcodes. php(900): um\core\Shortcodes->load_template(‘register’)\n#9 /nas/content/live/ testwebiste/wp-content/plugins/ultimate-member/includes/core/class-shortcodes. php(794): um\core\Shortcodes->template_load(‘register’, Array)\n#10 /nas/content/ live/testwebiste/wp-content/plugins/ultimate-member/includes/core/class-shortcodes. php(564): um\core\Shortcodes->load(Array)\n#11 /nas/content/live/testwebiste/ wp-includes/shortcodes.php(355): um\core\Shortcodes->ultimatemember(Array, ”,‘ ultimatemember’)\n#12 [internal function * Country: [https://share.getcloudapp.com/ApuvZZDA](https://share.getcloudapp.com/ApuvZZDA) [https://share.getcloudapp.com/P8u2JJ2l](https://share.getcloudapp.com/P8u2JJ2l) * State: [https://share.getcloudapp.com/NQuWyyW8](https://share.getcloudapp.com/NQuWyyW8) [https://share.getcloudapp.com/JrupKKeZ](https://share.getcloudapp.com/JrupKKeZ) * Can you please help us with this? * Thanks * The page I need help with: _[[log in](https://login.wordpress.org/?redirect_to=https%3A%2F%2Fwordpress.org%2Fsupport%2Ftopic%2Fdynamic-population-fields-cause-error%2F%3Foutput_format%3Dmd&locale=en_US) to see the link]_ Viewing 3 replies - 1 through 3 (of 3 total) * [missveronica](https://wordpress.org/support/users/missveronicatv/) * (@missveronicatv) * [3 years ago](https://wordpress.org/support/topic/dynamic-population-fields-cause-error/#post-16749475) * [@robertmurdock153](https://wordpress.org/support/users/robertmurdock153/) * You can try this code snippet: * ``` function custom_umwoo_country_list_dropdown() { $countries = WC()->countries->get_countries(); return $countries; } function custom_umwoo_get_states_dropdown() { $country_code = sanitize_text_field( $_POST['parent_option'] ); $valid_states = WC()->countries->get_states( $country_code ); return $valid_states; } ``` * Plugin Support [Yurii](https://wordpress.org/support/users/yuriinalivaiko/) * (@yuriinalivaiko) * [3 years ago](https://wordpress.org/support/topic/dynamic-population-fields-cause-error/#post-16752265) * Hello [@robertmurdock153](https://wordpress.org/support/users/robertmurdock153/) * This error appears because you use the wrong way to get states. Fix mistakes in your code: - use a proper way to get countries array: `WC()->countries->get_countries()` - use a proper way to get states array: `WC()->countries->get_states( $cc )` * Try this code: * ```wp-block-code function custom_umwoo_country_list_dropdown() { $countries = WC()->countries->get_countries(); return $countries; } function getStates() { if ( ! empty( $_POST['parent_option'] )&& is_string( $_POST['parent_option'] ) ) { $cc = sanitize_text_field( $_POST['parent_option'] ); $states = WC()->countries->get_states( $cc ); } return empty( $states ) ? array() : $states; } ``` * Regards * Plugin Support [andrewshu](https://wordpress.org/support/users/andrewshu/) * (@andrewshu) * [3 years ago](https://wordpress.org/support/topic/dynamic-population-fields-cause-error/#post-16775886) * Hi [@robertmurdock153](https://wordpress.org/support/users/robertmurdock153/) * This thread has been inactive for a while so we’re going to go ahead and mark it Resolved. * Please feel free to re-open this thread if any other questions come up and we’d be happy to help. 🙂 * Regards Viewing 3 replies - 1 through 3 (of 3 total) The topic ‘Dynamic Population fields cause error’ is closed to new replies. * ![](https://ps.w.org/ultimate-member/assets/icon-256x256.png?rev=3160947) * [Ultimate Member – User Profile, Registration, Login, Member Directory, Content Restriction & Membership Plugin](https://wordpress.org/plugins/ultimate-member/) * [Frequently Asked Questions](https://wordpress.org/plugins/ultimate-member/#faq) * [Support Threads](https://wordpress.org/support/plugin/ultimate-member/) * [Active Topics](https://wordpress.org/support/plugin/ultimate-member/active/) * [Unresolved Topics](https://wordpress.org/support/plugin/ultimate-member/unresolved/) * [Reviews](https://wordpress.org/support/plugin/ultimate-member/reviews/) * 3 replies * 4 participants * Last reply from: [andrewshu](https://wordpress.org/support/users/andrewshu/) * Last activity: [3 years ago](https://wordpress.org/support/topic/dynamic-population-fields-cause-error/#post-16775886) * Status: resolved