Table per Type inheritance in Entity Framework 7 beta 4

Question

I'm using Entity Framework 7 Beta 4 and need to map to an existing database.

The database uses a Table per Type hierarchy similar to this article (http://www.asp.net/mvc/overview/getting-started/getting-started-with-ef-using-mvc/implementing-inheritance-with-the-entity-framework-in-an-asp-net-mvc-application)

Here is a simple example:

public abstract class Person
{
    // SQL Table: Person
    // SQL Columns: PersonId, Name
    public long PersonId { get; set; }
    public string Name { get; set; }
    // This column would contain 'STUDENT' or 'PARENT'
    public string PersonType { get; set; }
}

public class Student : Person
{
    // SQL Table: Person_Student
    // SQL Columns: PersonId, GPA
    public decimal GPA { get; set; }
}

public class Parent : Person
{
    // SQL Table: Person_Parent
    // SQL Columns: PersonID, EmergencyContactNumber
    public string EmergencyContactNumber { get; set; }
}

public class PersonTestDb : DbContext
{
    public DbSet<Person> People { get; set; }
}

When trying to query the DbSet, I get this error:

The expression '[100001].People' passed to the Include operator could not be bound.

bricelam · Accepted Answer · 2016-02-05 17:27:29Z

3

We're still working on inheritance. (See issue #247.) TPH/STI is partially implemented, but not TPT. For now, you could do a direct mapping between the tables and classes. Something like:

class Person
{
    // Null when Parent
    public Student Student { get; set; }

    // Null when Student
    public Parent Parent { get; set; }
}

class Student
{
    public int PersonId { get; set; }
    public Person Person { get; set; }
}

class Parent
{
    public int PersonId { get; set; }
    public Person Person { get; set; }
}

edited Feb 5, 2016 at 17:27

answered May 15, 2015 at 21:44

bricelam

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3 Comments

Gareth Suarez Over a year ago

looks like TpT has been pushed back, and will not be in the first release. hopefully it will come fairly quickly after release.

ewahner Over a year ago

Parent is never used here... Did you mean to have public Parent Parent in the Person class?

Shimmy Weitzhandler Over a year ago

@bricelam thanks for the update. Any news? I'm about to start a new ASP.NET project, that TPT is a requirement. My question is can I use ASP.NET Core with the EF6? Then how about the Microsoft.AspNet.Identity.EntityFramework package? is there any official NuGet based alternative?

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