system.reflection.ambiguousmatchexception错误EF

Question

我有一个奇怪的情况。这部分代码：

List<Order> orders = orderRepository.Query().Where(x => x.del != true).ToList();

返回错误： System.Reflection.AmbiguousMatchException- Ambiguous match found.

更重要的是 - 如果没有下面的代码，一切正常。

如何解决？为什么我会收到这个错误？

Order.cs：

public partial class Order
{
    (..)
    public virtual Country UserCountry { get; set; }
    public virtual Country CompanyCountry { get; set; }
    public virtual DeliveryType UserDeliveryType { get; set; }
    public virtual PaymentType UserPaymentType { get; set; }
    //without that virtual properties everything works fine

}

MyContext.cs：

        modelBuilder.Entity<Order>()
            .HasRequired(u => u.UserCountry)
            .WithMany()
            .HasForeignKey(u => u.CountryID).WillCascadeOnDelete(false);


        modelBuilder.Entity<Order>()
            .HasRequired(u => u.CompanyCountry)
            .WithMany()
            .HasForeignKey(u => u.companyCountry).WillCascadeOnDelete(false);


        modelBuilder.Entity<Order>()
            .HasRequired(u => u.UserDeliveryType)
            .WithMany()
            .HasForeignKey(u => u.DeliveryTypeID).WillCascadeOnDelete(false);

        modelBuilder.Entity<Order>()
            .HasRequired(u => u.UserPaymentType)
            .WithMany()
            .HasForeignKey(u => u.PaymentTypeID).WillCascadeOnDelete(false);

        //and without that part of code