Question

Im simply trying to mock up a data model in POCO. But I’m a little confused about something. Lets just assume for this example that I will be using Entity Framework for ORM. First I have a Phone and Address class:

public class Phone
{
    int Id { get; set; }
    int Number { get; set; }
}

public class Address
{
    public int Id { get; set; }
    public string Street { get; set; }
    public string Suite { get; set; }
    public string City { get; set; }
    public string State { get; set; }
    public int Zip { get; set; }
}

Next I have a Person and a Company class:

public class Person
{
    int Id { get; set; }
    string FirstName { get; set; }
    string MiddleName { get; set; }
    string LastName { get; set; }
    string Prefix { get; set; }
}

public class Company
{
    int Id { get; set; }
    int Name { get; set; }
}

Say I want both Person and company to have Phone or address lists so logically the way I might think about this from a code perspective would to create an abstract class, AContact:

public abstract class AContact
{
    ICollection<Phone> Phone { get; set; }
    ICollection<Address> Address { get; set; }
}

And make my Company and Person then inherit this:

public class Company : AContact
{
    int Id { get; set; }
    int Name { get; set; }
}

public class Person : AContact
{
    int Id { get; set; }
    string FirstName { get; set; }
    string MiddleName { get; set; }
    string LastName { get; set; }
    string Prefix { get; set; }
}

Alternatively I might create an Interface:

public interface IContact
{
    ICollection<Phone> Phone { get; set; }
    ICollection<Address> Address { get; set; }
}

And Implement the interface:

public class Company : IContact
{
    public int Id { get; set; }
    public int Name { get; set; }
    public ICollection<Phone> Phone { get; set;}
    public ICollection<Address> Address {get; set;}
}

Now I understand the difference here between abstract classes and interfaces. But how is this supposed to be implemented for Entity Framework to function? From a little searching around on the web it seems that as of 4.1 you can not do the Interface thing, so does that mean I have to use the abstract class? OR do I just have to explicitly define both properties in every class I want to use them in? Also what about something like RavenDB would this work there as well?

Answer 1

Both options are possible.

When using your interface your DbContext will look like:

public class MyContext : DbContext
{
    public IDbSet<Company> Companies { get; set; }
    public IDbSet<Person> People { get; set; }
}

You will get back Companies and People objects that also happen to implement the interface you specify.

When using the abstract class you will have the following:

public class MyContext : DbContext
{
    public IDbSet<AContact> Contacts { get; set; }
}

With the abstract base class, you will have one entity set. With the OfType<T> you can filter the collection down to specific times.

RavenDB is a whole other subject. It’s a NoSql database that works really smooth. It serializes your objects to JSON and just stores them for you. You can use (almost) every class structure you want.