In PHP how do I rename a string in one function and use the result in a second function

Question

Pardon me if this is ultrabasic, I'm fairly green to all this.

I'm trying to fetch a string value (chapter name) from a wordpress database, use a php function to rename the value and then concatenate the renamed value with some other variables to create a member_id.

Below is my current code (added to functions.php file) and I have 2 problems with it:

1. From the 1st function, when I use the shortcode [member_chapter] in a page/post I always get PG no matter what value of chapter name was used to register. If I switch the order of the foreach statements, then I always get BB, i.e. I always get the return value of the first if statement no matter what chapter name is actually in the database.
2. From the 2nd function I never get the chapter_id, instead the result is always like FAL--2020-1007, i.e. it doesn't add the chapter_id value generated from the 1st function

I'd really appreciate any help.

/**
 * Fetch chapter name and return as 2-character chapter_id 
 * Create shortcode for viewing chapter_id 
 */
add_action('user_register', 'fetch_chapter');
function fetch_chapter(){
    $current_user = wp_get_current_user();
    $current_user_id = $current_user->ID;
    global $wpdb;
    $result = $wpdb->get_results('SELECT meta_value FROM usermeta WHERE meta_key = \'chapter_name\' AND user_id = ' . $current_user->ID);
    foreach($result as $row){
        if ($row->meta_value = 'Peregrine') {
            return $row->meta_value = 'PG';
        }elseif ($row->meta_value = 'Barbary') {
            return $row->meta_value = 'BB';
        }else { 
            return $row->meta_value;
        }
    }
}
add_shortcode('member_chapter', 'fetch_chapter'); 

/**
 * Generate unique_id
 * Retrieve chapter_id
 * Create member_id
 * Add member_id to user_meta table
 */
add_action('user_register', 'generate_member_id');
function generate_member_id($user_id){
    $unique_id = 1000 + $user_id;
    $chapter_id = fetch_chapter();
    $member_id = "FAL-" . $chapter_id . "-" . date("Y") . "-" . $unique_id;
    update_user_meta($user_id, 'member_id', $member_id);
}

Revised snippet

add_action('user_register', 'fetch_chapter');
function fetch_chapter(){
    $current_user = wp_get_current_user();
    $current_user_id = $current_user->ID;
    global $wpdb;
    $result = $wpdb->get_results('SELECT meta_value FROM usermeta WHERE meta_key = \'chapter_name\' AND user_id = '. $current_user->ID .' LIMIT 1');
    if ($result[0]->meta_value == 'Peregrine') {
           $result[0]->meta_value = 'PG';
    }elseif ($result[0]->meta_value == 'Barbary') {
           $result[0]->meta_value = 'BB';
    } 
     return $result[0]->meta_value;
}

add_action('user_register', 'generate_member_id');
function generate_member_id($user_id){
    $unique_id = 1000 + get_current_user_id();
    $chapter_id = fetch_chapter();
    $member_id = "FAL-" . $chapter_id . "-" . date("Y") . "-" . $unique_id;
    return $member_id;
}

add_shortcode('member_id', 'generate_member_id'); 

Answer 1

You have several mistakes! Please read more about program languages before writing programs. See PHP Tutorial

In first function you used assignment operator (which is =) instead of comparison operator (which is == or ===). You must change it everywhere use if in your code. Furthermore, You use return function inside foreach. it means your foreach loop runs just once and then return. You must use just if instead of foreach and use Limit 1 in your sql. Or do whatever to do in your loop and avoid to else return blahblah. Your second problem related to your first because it probably $row->meta_value is null for your first record returned.