Entity Framework Code First Composite Foreign Key on legacy DB

Question

So, I've been banging my head for a few days now and searching has led me nowhere close to a solution.

I have a legacy database thats far from following EF's code convention and I'm using EF Code First.

This is my actual situation: (Irrelevant fields ommited for the sake of brevity)

[Table("PEDIDO")]
public class Pedido : IValidatableObject
{
    [Key, Column(Order = 1), Required]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int CODIGO { get; set; }

    [Key, Column(Order = 2), ForeignKey("DadosCliente"), Required]
    public int CLIENTE { get; set; }
    public virtual Cliente DadosCliente { get; set; }

    public virtual ICollection<MaterialPedido> DadosMateriaisPedido { get; set; }

}


[Table("MATERIAL_PEDIDO")]
public class MaterialPedido : IValidatableObject
{
    [Key, Required, Column(Order = 1)]
    public int NRPEDIDO { get; set; } // This column relates to Pedido.CODIGO

    [Key, Required, Column(Order = 2), ForeignKey("DadosCliente")]
    public int CLIENTE { get; set; }
    public virtual Cliente DadosCliente { get; set; }

    [Key, Required, Column(Order = 3)]
    public string CODIGO { get; set; }
    // Please note that this column is some sort of "virtual field". Its value should be hard-coded to "P" when relating to the table "PEDIDO"
}

public class EntitiesContext : DbContext
{
     protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);

        modelBuilder.Entity<Pedido>()
            .HasKey(p => new { p.CLIENTE, p.CODIGO })
            .HasMany(x => x.DadosMateriaisPedido)
            .WithOptional(p => p.Pedido)
            .HasForeignKey(x => new { x.CLIENTE, x.NRPEDIDO })
            .WillCascadeOnDelete(false);
    }
}

As of now I'm getting the following error:

ProjetoPI.EF.Pedido_DadosMateriaisPedido: : Multiplicity conflicts with the referential constraint in Role 'Pedido_DadosMateriaisPedido_Source' in relationship 'Pedido_DadosMateriaisPedido'. Because all of the properties in the Dependent Role are non-nullable, multiplicity of the Principal Role must be '1'. Pedido_DadosMateriaisPedido_Target: : Multiplicity is not valid in Role 'Pedido_DadosMateriaisPedido_Target' in relationship 'Pedido_DadosMateriaisPedido'. Because the Dependent Role refers to the key properties, the upper bound of the multiplicity of the Dependent Role must be '1'.

What am I missing?Any help will be greatly appreciated!

Answer 1

So, I've finally found out what was happening so below is my solution for future reference and hoping it's able to help other desperate souls like me:

My mapping was entirely wrong. MATERIAL_PEDIDO has no relationship with PEDIDO (not sure I agree with this design, but...) and Entity Framework does not approve the creation of relationships that do not exist on the database. There is a third table that, besides containing MaterialPedido's children, its the relationship between Pedido and MaterialPedido.

[I can't post images, so I won't be able to post the DB Model =(]. So I cleared all relationships and started remodeling from scratch.

Here are my working relationships:

protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);

        modelBuilder.Entity<Pedido>()
            .HasKey(p => new { p.CLIENTE, p.CODIGO })
            .HasMany<DetalhePedido>(p => p.DetalhesPedido)
            .WithRequired(dp => dp.Pedido)
            .HasForeignKey(dp => new { dp.CLIENTE, dp.NRPEDIDO });

        modelBuilder.Entity<MaterialPedido>()
            .HasKey(mp => new { mp.NRPEDIDO, mp.CLIENTE, mp.CODIGO })
            .HasMany<DetalhePedido>(mp => mp.DetalhesPedido)
            .WithRequired(dp => dp.MaterialPedido)
            .HasForeignKey(dp => new { dp.NRPEDIDO, dp.CLIENTE, dp.MATERIAL });
    }

[Table("MATERIAL_PEDIDO")]
public class MaterialPedido : IValidatableObject
{
    [Key, Required, Column(Order = 1)]
    public int NRPEDIDO { get; set; }

    [Key, Required, Column(Order = 2), ForeignKey("DadosCliente")]
    public int CLIENTE { get; set; }
    public virtual Cliente DadosCliente { get; set; }

    [Key, Column(Order = 3)]
    public string CODIGO { get; set; }

    public virtual ICollection<DetalhePedido> DetalhesPedido { get; set; }

}

[Table("DETALHE_PEDIDO")]
public class DetalhePedido
{
    [Key, Column(Order = 1)]
    public int NRPEDIDO { get; set; }
    [Key, Column(Order = 2)]
    public int CLIENTE { get; set; }
    [Key, Column(Order = 3)]
    public string MATERIAL { get; set; }
    [Key, Column(Order = 4)]
    public string CODIGO { get; set; }

    public virtual Pedido Pedido { get; set; }
    public virtual MaterialPedido MaterialPedido { get; set; }
}

[Table("PEDIDO")]
public class Pedido : IValidatableObject
{
    [Key, Column(Order = 1), DisplayName("Cód Pedido"), Required]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int CODIGO { get; set; }

    [Key, Column(Order = 2), Required, CustomValidation(typeof(GranitoEntities), "NotZero")]
    public int CLIENTE { get; set; }
    [ForeignKey("CLIENTE")]
    public virtual Cliente DadosCliente { get; set; }

    public virtual ICollection<DetalhePedido> DetalhesPedido { get; set; }

}