在 Entity Framework Code First 中避免循环依赖

Question

假设我有两个实体：Nationality 和 Employee，关系为 1:n。

public class Employee
{
    public int Id { get; set; }
    // More Properties

    public virtual Nationality Nationality { get; set; }
}

public class Nationality
{
    public int Id { get; set; }
    public string Name { get; set; }
}

为了在实体框架中使用 Code-First，我必须再添加一个属性：Employees，我不希望将其添加到 Nationality 中（它会创建循环依赖）：

public class Nationality
{
    public int Id { get; set; }
    public string Name { get; set; }

    // How to avoid this property
    public virtual List<Employee> Employees { get; set; }
}

这样我就可以在Configuration类中配置关系1：n：

internal class EmployeeConfiguration : EntityTypeConfiguration<Employee>
{
    public EmployeeConfiguration()
    {
        HasKey(f => f.Id);

        HasRequired(e => e.Nationality)
          .WithMany(e => e.Employees)
          .Map(c => c.MapKey("NationalityId"));

        ToTable("Employees");
    }
}

是否有任何其他方法可以避免循环依赖并从Nationality 类中消除属性Employees？

Answer 1

使用WithMany() 重载配置映射。

internal class EmployeeConfiguration : EntityTypeConfiguration<Employee>
{
    public EmployeeConfiguration()
    {
        HasKey(f => f.Id);

        HasRequired(e => e.Nationality)
          .WithMany()
          .Map(c => c.MapKey("NationalityId"));

        ToTable("Employees");
    }
}