LDEV-4609 Calculate dates and status for archived progress
Methods which calculate LearnerProgress dates and status use ugly
instanceof constructs. There seem to be no good alternatives, though.
LearnerProgressArchive can inherit from LearnerProgress and we use
table-per-subclass Hibernate strategy. But then queries for
LearnerProgress would fetch also LearnerProgressArchive entities unless
in each HQL query we put "WHERE lp.class = LearnerProgress". It is easy
to forget plus generic methods like findAll() will not work well anyway.
LearnerProgress and LearnerProgressArchive can extend a new
AbstractLearnerProgress and we use table-per-concrete-class Hibernate
strategy. Same with CompletedActivityProgress and
CompletedActivityProgressArchive. But then
AbstractLearnerProgress.completedActivities will not let use both of
them due to lack of polymorphism in collections. Neither
Map<Activty, AbstractCompletedActivityProgress>
nor
Map<Activity, ? extends AbstractCompletedActivityProgress>
will not work. And this collection is the main reason why to do
inheritance in the first place.
Looking how the above solutions add complexity and little gain, these
few methods with instanceof seem to be a fine trade off.
