I am trying to find a way to build a model in Entity Framework to represent LearningJourneys, Courses and Lessons, where each course can have multiple Courses and lessons within it. However i also want to make it so lessons and courses can be used in multiple LearningJourneys.

So far my idea is to:

a) Make an entity for the LearningJourney to act as a Root for a tree structure.

public class LearningJourney
    {
        public Guid Id { get; set; }

    }

b) Make a LearningItem abstract class for Course and Lesson to store all common logic, and make inheriting Lesson and Course classes

   public abstract class LearningItem
    {
        public Guid Id { get; set; }
        public string Description { get; set; }
        public string Title { get; set; }
        public abstract bool CanHaveChildren { get;}
    }

   public abstract class Course : LearningItem
    {
        public override bool CanHaveChildren => true;
    }

    public abstract class Lesson : LearningItem
    {
        public override bool CanHaveChildren => false;
    }

c) Make a separate class to store relationships LearningJourneyLearningItem

    public class LearningJourneyLearningItem
    {
        public Guid Id { get; set; }
        public LearningJourney LearningJourney { get; set; }
        public LearningItem LearningItem { get; set; }
        public Guid? ParentNodeId { get; set; }
        public LearningItem? ParentNode { get; set; }
        public int OrderInParent { get; set; }
        public int Depth { get; set; }
    }

However I cannot figure out how to correctly set it up in the OnModelCreating.. or if it is at all a viable approach.

can someone suggest how to set this up?