Question

I use EF 5 with the code first approach. Now I try to define a “code” table in which I want to have several different codes (like address code, medium code, etc.). In this table I just have the following properties: ID (Guid), Name (String), Description (String) and a discriminator (in this case something like the type of the code: address code, medium code, etc.).

So I defined the following base class:

public abstract class Code : EntityBase
{
    public string Name { get; set; }
    public string Beschreibung { get; set; }
}

Then I derived two classes from code

public class AddressCode : Code {}
public class MediumCode : Code {}

The class EntityBase is abstract and just defines the Id property, we use it for every POCO class…

The goal is that I can use AddressCode as a property on my address POCO class:

public class Adresse : EntityBase
{
    #region Properties
    public string Name1 { get; set; }

    public virtual AddressCode AddressCode { get; set; }
    #endregion
}

The question now is, how can I explain EF how to do that? Anyone can help?

Thanks
Marco

---

Thanks for your answer!

I tried to do it like you said. Unfortunately I get an error because of my EntityBase class:

public abstract class EntityBase
{
    #region Properties

    public virtual Guid Id { get; set; }

    public virtual bool IsValid
    {
        get
        {
            {
                return Validate();
            }
        }
    }

    [NotMappedAttribute]
    public virtual IList<ValidationFailure> ValidationFailures { get; set; }

    #endregion

    #region Methods

    private bool Validate()
    {
        var validatorFactory = new AttributedValidatorFactory();
        IValidator validator = validatorFactory.GetValidator(GetType());

        if (validator == null)
        {
            return true;
        }

        ValidationResult validationResult = validator.Validate(this);

        ValidationFailures = validationResult.Errors;

        return validationResult.IsValid;
    }

    #endregion
}

The error message is:
You cannot use Ignore method on the property ‘ValidationFailures’ on type ‘Entities.AdresseCode’ because this type inherits from the type ‘Entities.EntityBase’ where this property is mapped. To exclude this property from your model, use NotMappedAttribute or Ignore method on the base type.

As you can see I already defined the property ValidationFailures as NotMapped but still I get this error.. Do you have an idea?

Thanks
Marco

Answer 1

Just create a context (derived from DbContext)

public class AddressesDb : DbContext
{
    public DbSet<Code> Codes { get; set; }
    public DbSet<Adresse> Adressen { get; set; }
}

And (when used in code) EF will create a database with default table and column names. It will create a discriminator column of type text (nvarchar) which will contain the names of the classes that derive from Code.

If you want different names and/or types you should either use data annotations or fluent API to configure these.