relationship problems in EF code-first

Question

I have two tables that i want to join Game and Details. Game has one Detail

The problem is that i cant bind the tables correct. The error i get is

"The entity types 'Game' and 'Details' cannot share table 'Details' because they are not in the same type hierarchy or do not have a valid one to one foreign key relationship with matching primary keys between them."

Here is my implementation

public class Game
{
    [Key]
    [ForeignKey("GameDetails")]
    public int GameId { get; set; }

    public string GameName { get; set; }

    //Navigation prop
    public virtual Details GameDetails { get; set; }
    public virtual ICollection<Details> DetailsId { get; set; }
}

public class Details
{
    [Key]
    public int DetailsId { get; set; }

    public int GameId { get; set; }
    public int RatingId { get; set; }

    public int Grade { get; set; }

    //Navigation prop
    [ForeignKey("DetailsId")]
    public virtual Game GameDetails { get; set; }
    public virtual RatingCompany RatingCompany { get; set; }
}

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Game>().HasKey(f => f.GameId);
        modelBuilder.Entity<Game>()
            .Map(m =>
                     {
                         m.Properties(b => new {b.GameId});
                         m.ToTable("Details");
                     });
    }

How can i bind it correctly with a 1-1 relationship?

Answer 1

You shouldn't use Map to configure a one-to-one relationship. Use the relationship methods of the fluent API instead.

Have a look at http://msdn.microsoft.com/en-us/data/jj591620.aspx#RequiredToRequired .

Answer 2

如果覆盖OnModelCreating，则不应具有属性属性。

Answer 3

OK, You can also do it using Data Annotation attributes:

• First of all you do not need to specify the foreign key in both entities, you just need to specify it in the dependent entity.
• Also in the Principal class you don't need to store the id of the dependent entity even if you want to have a reference to it.
• Also Since it is 1-1 relationship you don't need this line: public virtual ICollection DetailsId { get; set; }
  • From what you are saying Game is the principal entity and Detail is the dependent one.

The code can look like the following:

public class Game
{
    [Key]
    public int GameId { get; set; }

    public string GameName { get; set; }

    //Navigation prop
    public virtual Details GameDetails { get; set; }
}

public class Details
{
   [Key]
   [ForeignKey("Game")]
   public int GameId { get; set; }

   public int RatingId { get; set; }

   public int Grade { get; set; }

   //Navigation prop
   public virtual Game Game{ get; set; }
   public virtual RatingCompany RatingCompany { get; set; }
}