Question

I am creating a sort of family tree in entity framework 4.0. I have come across an issue where the Entity Framework is only loading the immediate children. It does not load the children of the children even though i have an include specified.

For example, this is my query :-

public IQueryable<TreeMember> GetTreeMembers(int userId)
        {
            return this.ObjectContext.TreeMembers.Include("RelatedTreeMembers").Where(u => u.UserId == userId && u.RelatedTreeMemberId == null);
        }

This would load the 1st level of children. But it does not load the children of the children. If i have to include children of the children, i have to write :-

public IQueryable<TreeMember> GetTreeMembers(int userId)
        {
            return this.ObjectContext.TreeMembers.Include("RelatedTreeMembers.RelatedTreeMembers").Where(u => u.UserId == userId && u.RelatedTreeMemberId == null);
        }

This is quickly getting to be frustrating because i don’t know how many times should i have to write this RelatedTreeMembers as a family tree can extend upto N level. How do i get past this issue? If my question is not clear please let me know.

Thanks in advance 🙂

Answer 1

That is how EF works. You want to define recursive (hierarchical) query which is not possible with eager loading in EF. You always have specify exactly which navigation properties you want to load – obviously in this scenario you can’t because you don’t know how deep is your recursion.

I like the idea @Magnus suggested with CTE but I would not use DB View. I would use stored procedure. The reason is that you already have entity TreeMember mapped to a table. If you define the view you will not be able to map it to the same entity type. You will need new entity for the view. If you use stored procedure you can map its result to already existing entity type.

Another way is to use lazy loading.