Add result of php function to WP database - php

Question

I have the following function to create a member_id:
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 . "-" . $unique_id;
return $member_id;
}
It appears to work fine and I can call the function from a shortcode and get the correct value.
Now I want to add the returned value to a database and have tried using
update_user_meta()
$wpdb->update
$wpdb->insert
$wpdb->query
all with necessary arguments but nothing seems to work.
I expected this to do it, but it just generates a generic error that I am not able to debug (I have a problem with error logging):
global $wpdb;
$users = $wpdb->get_results( "SELECT ID FROM $wpdb->users" );
$generated_id = generate_member_id()
if( $users ) {
foreach ( $users as $user ) {
update_user_meta( $user->ID, 'member_id', generate_member_id() );
}
}
However if I change generate_member_id() to a string like 'memberId', it works and the database is updated. So I don't know what I'm doing wrong. Why can't I add' the result of the generate_member_id() function and to a WP database?
EDIT
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;
}

Answer 1

There are a few things I notice that could cause problems:
You have this line that (1) has no ; at the end and (2) it doesn't look like you need it anyway - you don't use $generated_id anywhere:
$generated_id = generate_member_id()
You are not passing the user_id into generate_member_id for your users in the loop calling update_user_meta...
... but even if you did pass in the user_id, generate_member_id isn't using it anyway - it is using the current user id. That is the wrong value for the users in your loop.
You need to fix your generate_member_id function to work with the user_id parameter. I assume you want this function to work without one too, so it still gets the get_current_user_id is no user id is passed in:
add_action('user_register', 'generate_member_id');
function generate_member_id($user_id){
// If no user_id is passed in, use the current user id
if (!$user_id) $user_id = get_current_user_id();
$unique_id = 1000 + $user_id;
$chapter_id = fetch_chapter_id();
$member_id = "FAL-" . $chapter_id . "-" . $unique_id;
return $member_id;
}
And then remove the erroneous $generated_id... line and pass the user_id to the generate_member_id in your update_user_meta:
global $wpdb;
$users = $wpdb->get_results( "SELECT ID FROM $wpdb->users" );
if( $users ) {
foreach ( $users as $user ) {
update_user_meta( $user->ID, 'member_id', generate_member_id($user->ID) );
}
}