Fix for Undefined Variable $custom_fields in JSON_API_User_Controller Class

Hello Ali,

I noticed an issue in the JSON_API_User_Controller class related to the $custom_fields variable.

Currently, on line 731, the code looks like this:

if(is_array($custom_fields)){
    foreach ($custom_fields as $field => $value) {
        
        if(in_array($field, $disallowed) ){
            $json_api->error("This meta_key '".$field."' is not allowed.");
        }

        if ($field == 'cookie')
            continue;

        if (is_array($value)) {
            $values = array_map('trim', $values);
        } else {
            $values = trim($value);
        }

        if(!in_array($field, $disallowed) ){
            foreach($disallowed as $d){
                $field = str_replace($d, 'disallowed', $field); 
            }
            $result[$field]['updated'] = update_user_meta($user_id, $field, $values);
        }

    }
}

However, if the $custom_fields variable is not initialized, an error occurs:

Undefined variable $custom_fields in C:\wordpress\wp-content\plugins\json-api-user\controllers\User.php:731

To prevent this, I suggest adding a check for the existence of the $custom_fields variable. The modified code would look like this:

if(!empty($custom_fields) && is_array($custom_fields)){
    foreach ($custom_fields as $field => $value) {
        
        if(in_array($field, $disallowed) ){
            $json_api->error("This meta_key '".$field."' is not allowed.");
        }

        if ($field == 'cookie')
            continue;

        if (is_array($value)) {
            $values = array_map('trim', $values);
        } else {
            $values = trim($value);
        }

        if(!in_array($field, $disallowed) ){
            foreach($disallowed as $d){
                $field = str_replace($d, 'disallowed', $field); 
            }
            $result[$field]['updated'] = update_user_meta($user_id, $field, $values);
        }

    }
}

A similar adjustment is also needed on line 198:

if (!empty($custom_fields) && is_array($custom_fields)) {

Please consider implementing these changes to avoid potential errors.

Thank you!