EF映射一到多

我正在试图找出如何映射以下关系:

• "Relation"实体需要一个"Node"和一个"RelatedNode"

• 节点实体有一个"关系"(HasMany)集合，其中节点被要求是关系。Node OR Relation.RelatedNode.

当前映射得到的表如下所示:

[Id],[NodeId],[RelatedNodeId],[RelationType],[Node_Id]

[Node_Id]是自动创建的，这是我想避免的。

关系实体:

public class Relation
{
    private Relation()
    {
    }
    public Relation(int nodeId, int relatedNodeId)
    {
        NodeId = nodeId;
        RelatedNodeId = relatedNodeId;
    }
    public Relation(Node node, Node relatedNode)
    {
        Node = node;
        RelatedNode = relatedNode;
    }
    public int Id { get; set; }
    public int NodeId { get; set; }
    public Node Node { get; set; }
    public int RelatedNodeId { get; set; }
    public Node RelatedNode { get; set; }
    public RelationType RelationType { get; set; }
}

fluent api:

// Relation
modelBuilder.Entity<Relation>().Map(m =>
{
    m.ToTable("Relations");
});
modelBuilder.Entity<Relation>()
    .HasKey(t => t.Id)
    .Property(t => t.Id)
    .HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);
modelBuilder.Entity<Relation>().HasRequired(t => t.Node).
    WithMany().HasForeignKey(t => t.NodeId).WillCascadeOnDelete(false);
modelBuilder.Entity<Relation>().HasRequired(t => t.RelatedNode).
    WithMany().HasForeignKey(t => t.RelatedNodeId).WillCascadeOnDelete(false);

// Node
modelBuilder.Entity<Node>().Map(m =>
{
    m.MapInheritedProperties();
    m.ToTable("Nodes");
});
modelBuilder.Entity<Node>().HasMany(t => t.Relations);

modelBuilder.Entity<Node>().HasMany(t => t.Relations);