Question

I am trying to represent a graph with typed edges in an entity-framework code-first model. I am having quite a difficulty understanding how to set up the relationships correctly. I am calling the nodes in my graph ‘Items’ and the edges ‘Relationships’ Here is what I have:

public class Item : Learnable
{
    public Boolean IsBeginningItem { get; set; }
    public virtual List<Relationship> RelationshipsLeft { get; set; }
    public virtual List<Relationship> RelationshipsRight { get; set; }
}

–

public class Relationship : Learnable
{
    public Boolean IsPrerequisiteRelationship { get; set; }
    public virtual RelationshipType RelationshipType { get; set; }

    public int ItemLeftID { get; set; }
    [ForeignKey("ItemLeftID")]
    public virtual Item ItemLeft { get; set; }

    public int ItemRightID { get; set; }
    [ForeignKey("ItemRightID")]
    public virtual Item ItemRight { get; set; }
}

And here is what I am getting:

How can I get the RelationshipsRight property of Item to correspond to the ItemLeft property of Relationship AND the RelationshipsLeft property of Item to correspond to the ItemRight property of Relationship?

Oh… and I guess I should explain that this is supposed to be a directed graph that I can navigate bidirectionally. 🙂

Answer 1

You can use the [InverseProperty] attribute to bind the correct pairs of navigation properties together:

public class Relationship
{
    //...

    public int ItemLeftID { get; set; }
    [ForeignKey("ItemLeftID"), InverseProperty("RelationshipsRight")]
    public virtual Item ItemLeft { get; set; }

    public int ItemRightID { get; set; }
    [ForeignKey("ItemRightID"), InverseProperty("RelationshipsLeft")]
    public virtual Item ItemRight { get; set; }
}