I am using Timefold to model a relay-task planning system. I had modeled out my problem when using a single @PlanningVariable. The high level workflow is I get tasking, and it runs through a couple services to provide times a possible relay can happen. Giving me a collection of TimeSlots of when a relay can occur. So my @PlanningEntity is the Task. The Task has a @ValueRangeProvider of getPossibleTimeSlots() which is the getter for the collection of possible TimeSlots I received in a request. Then I use an over constrained design to weight these possible TimeSlots against each other to get a selectedTimeSlot which is my @PlanningVariable on the task entity.

Now I am looking at changing to a @PlanningListVariable,for reasons that it might take too long to explain here! I have been struggling though because my @ValueRangeProvider is on my @PlanningEntity because the range that the @PlanningListVariable should be able to select from is unique to the task, a different task should never access another tasks getPossibleTimeSlots(). According to the Timefold’s documentation a @ValueRangeProvider on a @PlanningEntity is not supported when using a @PlanningListVariable.

So I tried making a new @ValueRangeProvider method in my @PlanningSolution class that looked like the following.

@ValueRangeProvider(id = "timeSlotRange")
public List<TimeSlot> getTimeSlots(Task task) {
    return task.getPossibleTimeSlots();
}

This did not work as I get Failed to generate member accessor for the method....

Im assuming that the @ValueRangeProvider(id = "timeSlotRange") does not know what to do with the parameter.

With all this being said I am wondering what the correct way would be to handle this issue of having a per @PlanningEntity unique value range, while using the @PlanningListVariable. I looked at possibly storing all the TimeSlots in a common collection in my @PlanningSolution class, and looking at a variable listener for the possible timeslots for an induvial task, but I was not sure if this would be the way to go, or how to do it in the most efficient way. Any input helps Thanks!