EF代码优先。 相关实体未加载

Question

I've got Entity Framework Code First Entities:

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; }
}

It is supposed that a Customer has some Accounts for the Services. But there can be some default Accounts, which are not bounded to any Customer. And each Account is used for a concrete Service. This Entities have the following Configuration:

// 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();

The problem is, when I load a Customer, all his Accounts are loaded too, but they have their Service set to null. Why it is not loaded?

Thanks in advance

Answer 1

You need to load the entities. Based on your comment:

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

They should also be virtual if you want proxies for lazy loading... but for eager loading it's not necessary

Answer 2

Lazy loading of related entities requires the framework to create a proxy of your entity. Try making your navigation properties virtual:

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

Alternatively, eager-load the properties with Include or you can even explicitly load them with Load .

For more information, see https://msdn.microsoft.com/en-us/data/jj574232.aspx