MDL-71899 produces a regression. When an activity plugin is not present
but it has activities in the DB the course view returns an exception.
With this patch the code will ignore missing modules when calculating
the completion.

 - Modified SQL in get_data() to get the activity completion of all course modules without calling get_fast_modinfo() to reduce the DB queries.
 - Building activity completion cache for the whole course in one time instead of building the cache for each course module by passing $wholecourse = true to get_data()

For activity based course completion criteria allow instant
course completion updates if the activity completion state was changed
for a single user.

Activity modules may not have the associated grade_item created yet. It
used to throw fatal error in that case - even when trying to view the
course or edit the activity. So there was no easy way to recover from
this situation.

The patch is based on reasoning that an activity without grade item is
same as activity without any grades. And as such it is considered
incomplete.

A new unit test is added to cover this specific scenario. The existing
unit test is modified and it does not expect the exception any more.
There does not seem to be any good reason why this situation should be
exceptional.

When an automatic completion condition may have had its state change,
we now unset the cached value for the user's completion in the relevant
activity, so up-to-date values are re-fetched and available to students.
The previous behaviour was that custom conditions would remain cached
until the activity reached overall completion.

jun authored Mar 30, 2021 and Shamim Rezaie committed Apr 22, 2021

* *_get_completion_state() callback functions have been deprecated and
should no  longer be used. Plugins that define custom completion rules
must implement the mod_[modname]\completion\custom_completion class that
extends the \core_completion\activity_custom_completion base class.

Simey Lameze authored Mar 09, 2021 and jun committed Apr 02, 2021

Part of MDL-70817

This class would belong more appropriately within the 'user' API
(core_user) instead of within the 'core' API, since it is
directly related to user data.

Since the class has only just been added to Moodle, now is a good
time to move it.

We should be able to fetch the grade completion status for modules
that do not have custom completion configured. This also improves
unit testing coverage.

jun authored Mar 10, 2021 and Sara Arjona committed Mar 10, 2021

Since cm_info::customdata can be of any type, we need to cast it to an
array first before checking for custom completion rules. Otherwise,
an exception can be thrown (e.g. customdata has been set as an stdClass)

In all cases changes have been kept to a minimum while not making
the code completely horrible. For example, there are many instances
where it would probably be better to rewrite a query entirely, but
I have not done that (in order to reduce the risk of changes).

* Update completion_info::get_data() to add other completion
information from a new method called get_other_cm_completion_data().
This allows the storage of the completion statuses of the following
completion rules to completion_info objects:
  - 'Students must receive a grade' completion rule.
  - Any custom completion rule defined by an activity.
This allows detailed completion information to be fetched for course
modules.
It also allows custom completion statuses to be cached which will help
reduce DB queries when fetching completion statuses.
* Update update_state() to fetch overall completion state from the
module's activity_custom_completion implementation. Falls back to the
*_get_completion_state() callback function.
* Update internal_set_data() to include the other cm completion data
in the updated cache data for the module instance.

Move the current logic for determining the completion status for the
"Student must receive grade" completion rule to a function so it cann
be reused.
Unit test included.

Changes:
- Activities with auto completion and a completion status overridden to
COMPLETION_COMPLETE are no longer processed by normal completion
triggers.
- All activities can still be completed by students when their
completion status has been overridden to COMPLETION_INCOMPLETE, via
either auto or manual triggers.
- Completion unit tests updated

Thanks to Nick Phillips for initial patch

The last change added 1 db read per course per page which is not OK. Add a cache to compensate.

The completion cache is currently not marked as simpledata. On the
course page it is frequently retrieved hundreds of times which results
in many calls to the slow unserialize function. By making a slight
change to the data format (using arrays instead of objects) we can
mark it as simpledata, which will avoid using unserialize.

And add a unit test covering completion_can_view_data() without
full course object passed.

The activity completion report wasn't showing the additional name fields.