Question

I have an abstract superclass DataContent:

public abstract class DataContent
{
    [Key(), DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int Id { get; set; }
    [ForeignKey("Sheet")] //Foreign Key van Sheet
    public int SheetId { get; set; }
    public string Name { get; set; }

    public DataContent(int i, string n)
    {
        Id = i;
        Name = n;
    }

and 3 subclasses, for example EmptyContent:

public class EmptyContent: DataContent
{

    //TODO: Do these keys have to be here as well???
    [Key(), DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int Id { get; set; }
    [ForeignKey("Sheet")] //Foreign Key van Sheet
    public int SheetId { get; set; }

    public string Name { get; set; }
    public string Text { get; set; }


    public EmptyContent (int i, string n) : base(i,n)
    {
        Text = "";

    }

}

My question is: Do I have to declare the (foreign) keys twice for the Entity Framework to generate the database? or can I just put them in the superclass Datacontent only?

[Still a student so sorry if this question seems stupid to you :)]

Answer 1

Each property can be implemented only once (name must be unique in the whole hierarchy). Your derived classes shouldn’t have any properties from the base class unless they override them.