entity framework code first - shared 1-to-many ent

Question

I've been going around the block a couple of times on this, so I'm taking a fresh approach. I would like to figure out if it possible to have a single entity that is on the many-side of multiple 0-to-many relationships. This is what I'm trying to do:

A Client has 0-to-many Phones

public class Client
{
  [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
  public int ClientId { get; set; }
  public string Name { get; set; }

  public virtual ICollection<Phone> Phones { get; set; }
}

A Business has 0-to-many Phones

public class Business
{
  [Key]
  [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
  public int BusinessId { get; set; }
  public string Name { get; set; }

  public virtual ICollection<Phone> Phones { get; set; }
}

And here is Phones:

public class Phone
{
  [Key]
  [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
  public int PhoneId { get; set; }

  public string Number { get; set; }
}

Of course, the problem with the Phones property in Business/Client is that this creates FK's in Phone to both Client and Business, which clutters-up Phones.

So, I saw another poster try creating a manual join table, but it seemed to be geared to the many-side participating in one relationship:

public class ClientPhone
{
  public int ClientID { get; set; }
  public int PhoneID { get; set; }

  public virtual Client Client { get; set; } // One Client
  public virtual Phone Phone { get; set; } // One Phone
} 

Should I split Phone up into ClientPhones and BusinessPhones 'normal' entities using traditional 0-to-many relationships. If someone could give me some advice on the cleanest way to to model this, it would be very appreciated.

Thanks!

Answer 1

I think you can model this using table per hierarchy method ,

public class Client
{
  [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
  public int ClientId { get; set; }
  public string Name { get; set; }

  public virtual ICollection<ClientPhone> Phones { get; set; }
}


public class Business
{
  [Key]
  [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
  public int BusinessId { get; set; }
  public string Name { get; set; }

  public virtual ICollection<BusinesPhone> Phones { get; set; }
}


public class Phone
{
  [Key]
  [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
  public int PhoneId { get; set; }

  public string Number { get; set; }
}

public class BusinesPhone:Phone
{

}

public class ClientPhone:Phone
{

}

This will create one table for both client and business phone with a discriminator column. Then you can easily separate client and business phones.