$event->id does not exist in multiple places.

[caperneoignis]

Description
When going through a quiz, with the logstore app set to real time transmission to the LRS. I get the following in several places.

Notice: Undefined property: stdClass::$id in {web_directory}\moodle\admin\tool\log\store\xapi\src\transformer\events\mod_quiz\attempt_viewed.php on line 37

And again at transformer\handler.php line 37

$eventobj->id is undefined.
Version

• master, version 2018073005

Steps to reproduce the bug

1. Have debugging turned on for moodle.
   Go and take a quiz, and look at the bottom, you will see several undefined warnings.

Expected behaviour

• No warnings, because the id has either been set, or there is a check to replace the value with the expected value, or ignore the value all together.

Actual behaviour

• The id is not being set in the stdClass causing errors and in some cases bad values/no event sent.

[caperneoignis]

We can not assume event will have an id, we need to handle this/assign this appropriately.

[ryasmi]

Yeah I'd recommend checking if it's there and setting it to null if not.

[caperneoignis]

Any opposition to using a ternary expression in those spots? And to use zero instead of null since null can put us back into the undefined boat depending on where that element ends up?

[ryasmi]

I can see four uses of the event's id.

1. /src/transformer/events/mod_quiz/attempt_viewed.php#L37
2. /src/loader/lrs.php#L70
3. /src/transformer/handler.php#L46
4. /classes/task/emit_task.php#L46

Let me know if there are any other uses. I think the first usage is actually meant to be $event->objectid rather than the $event->id. If that's the case, we should probably just avoid using the event id, except where it's absolutely needed like the 4th usage where the id will have to exist.

[caperneoignis]

That's agreeable.