包括抽象父EF代码优先对象的列表

Question

I have an abstract class named Business that looks like this:

public abstract class Business
{
  public int Id { get; set; }
  public string Name { get; set; }
  public string TaxNumber { get; set; }
  public string Description { get; set; }
  public string Phone { get; set; }
  public string Website { get; set; }
  public string Email { get; set; }
  public bool IsDeleted { get; set; }
  public virtual IEnumerable<Address> Addresses { get; set; }
  public virtual IEnumerable<Contact> Contacts { get; set; }
}

One of the classes that inherits from the above is the Supplier class. That looks like this:

public class Supplier : Business
{
  public virtual ICollection<PurchaseOrder> PurchaseOrders { get; set; }
}

All is good, but when I come to grab a supplier for my MVC front-end, I would like to include the Addresses associated with the Supplier.

I tried this:

public Supplier GetSupplier(int id)
{
  return _context.Businesses.Include(b => b.Addresses).OfType<Supplier>().SingleOrDefault(x => x.Id == id);
}

But it doesn't work, it says there is no Addresses property on Supplier .

Answer 1

如果将集合从IEnumerable更改为ICollection，则代码应该可以正常工作

Answer 2

You must implement an override since the base class is abstract.

From MSDN

"Members marked as abstract, or included in an abstract class, must be implemented by classes that derive from the abstract class"

Or alternatively remove the abstract keyword so that the base is used by default.

Another alternative, remove the base and use an Interface instead unless you have a specific reason for using abstract classes.