EF代码优先。相关实体未加载

Question

我有 Entity Framework 个代码优先实体：

public class Customer
{
   public long Id { get; set; }
   public ICollection<ServiceAccount> Accounts { get; set; }
}

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

public class ServiceAccount
{
   public long Id { get; set; }
   public Customer Customer { get; set; }
   [Required()]
   public Service Service { get; set; }
}

假定客户有一些服务帐户。但是可以有一些默认帐户，这些帐户不受任何客户的约束。每个帐户都用于一个具体的服务。此实体具有以下配置：

// Customer Configuration:
base.ToTable("Customers");
base.HasKey(x => x.Id);
base.HasMany(x => x.ServiceAccounts)
    .WithOptional(x => x.Customer)
    .WillCascadeOnDelete();
// For Service:
base.ToTable("Services");
base.HasKey(x => x.Id);
// For Account:
base.ToTable("Accounts");
base.HasKey(x => x.Id);
base.HasOptional(x => x.Customer)
    .WithMany(x => x.Accounts);
base.HasRequired(x => x.Service)
    .WithMany();

问题是，当我加载客户时，他的所有帐户也都加载了，但他们的服务设置为空。为什么没有加载？

提前致谢

Answer 1

延迟加载相关实体需要框架创建实体的代理。尝试将您的导航属性虚拟化：

public class ServiceAccount
{
   public long Id { get; set; }
   public virtual Customer Customer { get; set; }
   [Required]
   public virtual Service Service { get; set; }
}

或者，使用 Include 预先加载属性，或者您甚至可以使用 Load.

显式加载它们

有关详细信息，请参阅 https://msdn.microsoft.com/en-us/data/jj574232.aspx

Answer 2

您需要加载实体。根据您的评论：

IQueryable<Customer> customers = Customers.Include(x => x.Accounts.Select(y => y.Service));

如果您想要延迟加载的代理，它们也应该是 virtual...但是对于预加载，则没有必要

EF代码优先。相关实体未加载

EF Code First. Related Entity is not loading

c#

entity-framework

code-first