Scaffolding model with inheritance in ASP.NET MVC 3 and Entity Framework

Question

I'm trying out the new scaffolding features in MVC 3, using Entity Framework Code First. My model looks like this:

public abstract class A
{
    public int Id { get; set; }
}

public class B : A
{
    public string Name { get; set; }
}

public class MyContext : DbContext
{
    public DbSet<A> As { get; set; }
}

I create a new controller using the new controller wizard in MVC and select to scaffold type A. CRUD code is generated and I can successfully start the project in a webbrowser. When I try to create a new A, I get the following error message:

"Cannot create an abstract class"

which makes sense. A is abstract.

Can I use scaffolding to create B's and other inherited classes from A?

Arialdo Martini · Accepted Answer · 2014-03-10 16:48:41Z

2

AFAIK you should add a

using System.ComponentModel.DataAnnotations;

[Table("TableNameForB")]
public class B : A
{
    public string Name { get; set; }
}

as attribute for your concrete class

Find here a complete example

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.Entity;
using System.ComponentModel.DataAnnotations;

namespace ZooLabPoco
{
    public class Context : DbContext
    {
        public DbSet<Animal> Animals { get; set; }
        public DbSet<Zoo> Zoos { get; set; }
    }

    public class Zoo
    {
        public int Id { get; set; }
        public virtual ICollection<Animal> Animals { get; set; }
        public Zoo()
        {
            this.Animals = new List<Animal>();
        }
    }

    public abstract class Animal
    {
        public int Id { get; set; }
        public int ZooId { get; set; }
        public virtual Zoo Zoo { get; set; }
    }

    [Table("Lions")]
    public class Lions : Animal
    {
        public string LionName { get; set; }
    }

    [Table("Tigers")]
    public class Tigers : Animal
    {
        public string TigerName { get; set; }
        public int TailLength { get; set; }
    }

    class Program
    {
        static void Main(string[] args)
        {

            var context = new Context();
            context.Database.Delete();
            context.Database.CreateIfNotExists();


            var zoo = new Zoo();
            zoo.Animals.Add(new Lions { LionName = "Fritz" });
            zoo.Animals.Add(new Lions { LionName = "Jerry" });
            zoo.Animals.Add(new Tigers { TigerName = "Pluto" });

            context.Zoos.Add(zoo);
            context.SaveChanges();

        }
    }
}

edited Mar 10, 2014 at 16:48

answered Nov 9, 2011 at 16:28

Arialdo Martini

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2 Comments

Matthew Hudson Over a year ago

The two examples in this answer conflict with each other. The first uses "TableNameForA" (Base Table Name), whereas the second uses the Concrete Table Name: "Lions" instead of "Animals". Which is correct?

Arialdo Martini Over a year ago

The name that must be submitted is for the concrete class. Thank you for the warning!

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