Question

I have a question about how I define the entries when I work with “Code First”.

I am defining the following class with these data annotations:

public class Producto
{
    [Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int ProductoID { get; set; }

    [ForeignKey("Parque"),Required]
    public int FKParque { get; set; }
    [ForeignKey("FKParque"), Required]
    public virtual Parque Parque { get; set; }

    public string Nombre { get; set; }
}

The question is:Should I put the data annotation “Required” in the navigation property “Parque”?
If I put the data annotation, when I try to do:

using (MiContexto contexto = new MiContexto()) {
            Producto nuevoProducto = new Producto();
            nuevoProducto.Nombre = "nuevo";
            nuevoProducto.FKParque = 1;

            contexto.Productos.Add(nuevoProducto);

            contexto.SaveChanges();
}

An error occurs because the navigable property is null and is marked as required.

What would be the right approach?

Sorry if my English is not very good.

Thx.

Answer 1

I think placing the required attribute on the FKParque is sufficient. The navigation property isn’t populated until the object is saved/retrieved from the database, so could potentially be null, even if the foreign key can’t be.