Multiple level inheritance. Entity Framework C#

Question

I have been working with inheritance on Entity Framework 6 (code-first) with Visual Studio 2015. At this point I wanted to try Multiple Inheritance like this (This is a summary not the exactly syntaxt):

public abstract class Person {
    public String Name
    public String LastName
}

public class Teacher : Person {
    [Key]public int Id_Teacher
}

public class Student : Person {
    [Key] public int Id_Student
    public string code_s
}

public class ExchangeStudent : Student {
    [Key] public int Id_ExchangeStud
    public string HomeUniversity
}

I have made the first step that is create Person and the Child tables Teacher & Student, but when it comes to create the third child table it don't work.

I used TPC for the first step so in the Context I got DbSet of Students and Teachers.

Is there any way to implement the third table EXCHANGE STUDENT??

Thanks you so much.

what is the issue you are facing?? And all the members dont have semicolon. Is it a property or variable — Power Star
– Power Star, Commented Aug 21, 2017 at 15:15
Don't override the primary key property. Put that in the base class, call it ID and use ti for all your derived classes. — DavidG
– DavidG, Commented Aug 21, 2017 at 15:20

Vignesh · Accepted Answer · 2017-08-21 15:49:02Z

If I understand correctly, your Model design should look like below,

    public class Person
    {
        [key] //No need to mention [key] annotation here, Because EF will automatically understand Id property will act as Primary Key.
        public int Id { get; set; }
        public string Name { get; set; }
        public string LastName { get; set; }
    }

    public class Teacher: Person
    {

    }

    public class Student: Person
    {
        public string Code { get; set; }
    }

    public class ExchangeStudent : Student
    {

        public string HomeUniversity { get; set; }
    }

You have to avoid each [Key] properties in each child classes. Base Class will have an Id property which will act as a PrimaryKey for the Table and all other child class.

If you follow the above, after applying the migration script into the Table, System will create a Table(Persons) with Discriminator column for the child class.

Hope this may help you to move forward!

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