实体框架一对多和多对多关系

Question

im currently learning the entity framework and been miserably failing with this task for a couple of days... I would like to achieve the following Database Scheme:

TableA:
ClassA_ID
ClassB_ID(foreign key - one to one)

TableATableB:(one-to-many relationship)
ClassA_ID
ClassB_ID

TableB:
ClassA_ID(foreign key - one to one)
ClassB_ID

So I Actually want a specific one to one relationship from Class A to Class B and a one to many Relationship from ClassA to ClassB.

My C# Code Looks like this:

Class A:

public static int idcounter;
[Key]
public int id { get; set; }
public virtual List<ClassB> allClassB { get; set; }
public virtual ClassB currentClassB { get; set; }
public int? currentClassBID { get; set; }

public ClassA(){
    idcounter++;
    id = idcounter;
    allClassB = new List<ClassB>();
    currentClassB = new ClassB();
    currentClassBID = currentClassB.id;
    MyContext.add(this);
}

Class B:

public static int idcounter;
[Key]
public int id { get; set; }
public virtual ClassA owner { get; set; }
public int? ownerID { get; set; }

public ClassB(ClassA a){
    idcounter++;
    id = idcounter;
    owner = a;
    ownerID =  a.id;
}

MyContext:

public static void add(ClassA a)
    {
        using (MyContext context = new MyContext ())
        {
            context.setB.Add(a.currentClassB);
            context.setA.Add(a);
            context.SaveChanges();           
        }
    }

protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Entity<ClassA>().HasOptional(x => x.currentClassB ).WithMany().HasForeignKey(x => x.currentClassBID ).WillCascadeOnDelete(false);
        modelBuilder.Entity<ClassB>().HasOptional(x => x.ClassA).WithMany(x => x.allClassB).HasForeignKey(x => x.ownerID).WillCascadeOnDelete(false) ;
    }

Its pretty similar to this question Entity Framework Code First: How can I create a One-to-Many AND a One-to-One relationship between two tables? but I just get a Circular Exception when saving.

Unable to determine a valid ordering for dependent operations. Dependencies may 
exist due to foreign key constraints, model requirements, or store-generated 
values.

Its pretty weird that after

context.setA.Add(a);

it adds currentClassB into allClassB without me ever mention that... it Even suddenly does that when i dont

allClassB = new List<ClassB>();

What am I doing wrong?

Answer 1

You have to use InverseProperty as shown below.

[InverseProperty("allClassB")]
public virtual ClassB currentClassB { get; set; }
public int? currentClassBID { get; set; }

DataAnnotations - InverseProperty Attribute: