Transforming event having userid=0 creates exception

[Callustian]

Description

• The transformer generates exceptions if the userid = 0 ( \core\event\course_viewed and \core\event\user_created). More generally the user ( guest? ) is not in the database, so every transformer that uses it fails.

Version

• https://github.com/xAPI-vle/moodle-logstore_xapi/releases/download/v4.2.5/xapi.zip

Steps to reproduce the bug

1. I am using Moodle, and I am unsure of how it is generating the event as guest, at the moment. This feature is not checked.

Expected behaviour

• events having userid=0 should be transformed because they exist.

Actual behaviour

• events having userid=0 create exception.

Server information

• Moodle+mysql.

Client information

• OS: linux
• Browser: chrome 78.0.3904.70 (Official Build) (64-bit)

Thank you.

[davidpesce]

@Callustian - which version of the plugin are you using?

[Callustian]

@davidpesce Thank you for your reply.

I am using v4.2.5.

[mlynn-lp]

@Callustian @davidpesce @gordonmacqueen-lp @Patches- @lzabo
Suggested code change in these methods:

    // Get a valid user for guest.
    $guest = false;
    if ($event->userid == 0) {
        $guest = true;
        if (isset($CFG->siteguest)) {
            $event->userid = $CFG->siteguest;
        }
    }
    $user = $repo->read_record_by_id('user', $event->userid);

    // Reset userid so it is the same as in logstore_standard_log.
    if ($guest == true) {
        $event->userid = 0;
    }

Would it be possible to create a branch and put this in for code review in the following files:
course_viewed.php
user_created.php