EF例外，如何首先在C＃和实体框架代码中为地址建模

EF引发以下异常：

System.InvalidOperationException：引用完整性约束冲突。从属角色具有多个具有不同值的主体。

我有两个实体，即StateProvince和Country：

public class StateProvince
{
    public long Id { get; set; }

    [StringLength(100)]
    public string Name { get; set; }

    public long CountryId { get; set; }
    public Country Country { get; set; }
}

public class Country
{
    public long Id { get; set; }

    [StringLength(2)]
    public string Code { get; set; }

    public IEnumerable<StateProvince> StatesProvinces { get; set; }
}

和两个使用它们的实体：

public class Customer
{
    public long Id { get; set; }

    public long BillingStateProvinceId { get; set; }
    [ForeignKey("Id")]
    public StateProvince BillingStateProvince { get; set; }

    public long BillingCountryId { get; set; }
    [ForeignKey("Id")]
    public Country BillingCountry { get; set; }

    public long ShippingStateProvinceId { get; set; }
    [ForeignKey("Id")]
    public StateProvince ShippingStateProvince { get; set; }

    public long ShippingCountryId { get; set; }
    [ForeignKey("Id")]
    public Country ShippingCountry { get; set; }
}

public class Vendor
{
    public long Id { get; set; }

    public long StateProvinceId { get; set; }
    public StateProvince StateProvince { get; set; }

    public long CountryId { get; set; }
    public Country Country { get; set; }
}

在我的OnModelCreating中：

protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Customer>()
            .HasRequired(m => m.ShippingStateProvince)
            .WithOptional().WillCascadeOnDelete(false);

        modelBuilder.Entity<Customer>()
            .HasRequired(m => m.ShippingCountry)
            .WithOptional().WillCascadeOnDelete(false);

        modelBuilder.Entity<Customer>()
            .HasRequired(m => m.BillingStateProvince)
            .WithOptional().WillCascadeOnDelete(false);

        modelBuilder.Entity<Customer>()
            .HasRequired(m => m.BillingCountry)
            .WithOptional().WillCascadeOnDelete(false);

        modelBuilder.Entity<Vendor>()
            .HasRequired(m => m.StateProvince)
            .WithOptional().WillCascadeOnDelete(false);

        modelBuilder.Entity<Vendor>()
            .HasRequired(m => m.Country)
            .WithOptional().WillCascadeOnDelete(false);

        base.OnModelCreating(modelBuilder);
    }

最后，引发异常的代码：

[TestMethod]
    public void TestMethod1()
    {
        Db db = new Db();

        #region Set/reset items

        Country us = db.Countries.FirstOrDefault();
        if (us == null)
        {
            us = new Country { Code = "US" };
            db.Countries.Add(us);
            db.SaveChanges();
        }
        long usId = us.Id;

        List<StateProvince> states = db.StateProvinces.ToList();
        StateProvince mass = states.Where(m => m.Name == "MA").FirstOrDefault();
        StateProvince ct = states.Where(m => m.Name == "CT").FirstOrDefault();
        if (mass == null)
        {
            mass = new StateProvince { Name = "MA", CountryId = usId };
            ct = new StateProvince { Name = "CT", CountryId = usId };
            db.StateProvinces.Add(mass);
            db.StateProvinces.Add(ct);
            db.SaveChanges();
        }
        long massId = mass.Id;
        long ctId = ct.Id;

        List<Customer> customersToRemove = db.Customers.ToList();
        db.Customers.RemoveRange(customersToRemove);
        db.SaveChanges(); 

        #endregion

        Customer customerToAdd = new Customer { 
            BillingStateProvinceId = massId, 
            ShippingStateProvinceId = ctId, 

            ShippingCountryId = usId, 
            BillingCountryId = usId,

            BillingStateProvince = mass,
            ShippingStateProvince = ct,

            BillingCountry = us,
            ShippingCountry = us
        };

        db.Customers.Add(customerToAdd);

        try
        {
            //exception thrown here
            db.SaveChanges();
        }
        catch (Exception e)
        {
            throw;
        }

        db.Dispose();

        Db dbCheck = new Db();

        Customer customer = dbCheck.Customers.Include(m => m.BillingStateProvince).Include(m => m.ShippingStateProvince).FirstOrDefault();

        dbCheck.Dispose();
    }

我怀疑问题是我没有正确使用[ForeignKey]属性，还是我在OnModelCreating中做错了什么。如果我在客户实体中只有一个StateProvince和一个Country实体，则可以使它工作，但是，一旦有两个，就无法解决。有什么帮助吗？

从更广泛的角度来看，没有人链接到博客/帖子/文章/教程，这些链接涉及如何首先使用c＃EF代码对地址进行建模？我碰到了一个使用[ComplexType]属性的应用程序，问题是我无法在其中封装StateRegion和Country类。我目前的想法是将每个类的各个地址字段都烘烤，即MailingStreetAddress，BillingStreetAddress等。我想看看其他人如何处理地址，以更好地理解自己的地址。

编辑

我是@@ Sam，我尝试将属性更改为：

[ForeignKey("BillingStateProvinceId")]

每个属性。删除/重新创建数据库后，EF抛出此错误：

Customer_BillingCountry_Source：：多重性在关系“ Customer_BillingCountry”中的角色“ Customer_BillingCountry_Source”中无效。由于从属角色属性不是关键属性，因此从属角色多重性的上限必须为'。Customer_BillingStateProvince_Source ：：多重性在关系“ Customer_BillingStateProvince”中的角色“ Customer_BillingStateProvince_Source”中无效。由于从属角色属性不是关键属性，因此从属角色多重性的上限必须为''。Customer_ShippingCountry_Source：：多重性在关系“ Customer_ShippingCountry”中的角色“ Customer_ShippingCountry_Source”中无效。由于从属角色属性不是关键属性，因此从属角色多重性的上限必须为'。Customer_ShippingStateProvince_Source：：多重性在关系“ Customer_ShippingStateProvince”中的角色“ Customer_ShippingStateProvince_Source”中无效。由于从属角色属性不是关键属性，因此从属角色多重性的上限必须为'。

编辑2

对于每个@Steve Green，更改了我的StateRegion，Country实体和OnModelCreating，现在当我删除重新创建db时会引发此错误：

指定的架构无效。错误：由于类型“ StackOverflow.Country”不可用，因此未加载关系“ StackOverflow.Customer_ShippingCountry”。

我编辑的代码：

public class StateProvince
{
    public long Id { get; set; }

    [StringLength(100)]
    public string Name { get; set; }

    //new properties
    public ICollection<Customer> Customers { get; set; }
    public ICollection<Vendor> Vendors { get; set; }

    public long CountryId { get; set; }
    public Country Country { get; set; }
}

public class Country
{
    public long Id { get; set; }

    [StringLength(2)]
    public string Code { get; set; }

    //new properties
    public ICollection<Customer> Customers { get; set; }
    public ICollection<Vendor> Vendors { get; set; }

    public IEnumerable<StateProvince> StatesProvinces { get; set; }
}

而我的OnModelCreating反映了他的观点：

protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Customer>()
            .HasRequired(m => m.ShippingStateProvince)
            .WithMany(m => m.Customers)
            .HasForeignKey(m => m.ShippingStateProvinceId);

        modelBuilder.Entity<Customer>()
            .HasRequired(m => m.ShippingCountry)
            .WithMany(m => m.Customers)
            .HasForeignKey(m => m.ShippingCountryId)
            .WillCascadeOnDelete(false);

        modelBuilder.Entity<Customer>()
            .HasRequired(m => m.BillingStateProvince)
            .WithMany(m => m.Customers)
            .HasForeignKey(m => m.BillingStateProvinceId)
            .WillCascadeOnDelete(false);

        modelBuilder.Entity<Customer>()
            .HasRequired(m => m.BillingCountry)
            .WithMany(m => m.Customers)
            .HasForeignKey(m => m.BillingCountryId)
            .WillCascadeOnDelete(false);

        modelBuilder.Entity<Vendor>()
            .HasRequired(m => m.StateProvince)
            .WithMany(m => m.Vendors)
            .HasForeignKey(m => m.StateProvinceId)
            .WillCascadeOnDelete(false);

        modelBuilder.Entity<Vendor>()
            .HasRequired(m => m.Country)
            .WithMany(m => m.Vendors)
            .HasForeignKey(m => m.CountryId)
            .WillCascadeOnDelete(false);

        base.OnModelCreating(modelBuilder);
    }