实体框架代码首先一对一可选

Question

I have relation one to one with following objects:

[DataContract(IsReference = true)]
public class Ecwid
{
    [Key, ForeignKey("Project")]
    [DataMember]
    public Guid ProjectId { get; set; }

    [DataMember]
    public string EcwidShopID { get; set; }

    public virtual Project Project { get; set; }
}

[DataContract]
public class Project : AuditInfoComplete
{
    [Key]
    [DataMember]
    public Guid ProjectId { get; set; }

    [DataMember]
    public virtual Ecwid Ecwid { get; set; }
}

In DbContext I have:

    modelBuilder.Entity<Ecwid>().HasKey(p => p.ProjectId);
    modelBuilder.Entity<Project>().HasOptional(p => p.Ecwid).WithRequired(p => p.Project);

Problem: when I create Project, Entity Framework creates Ecwid object in database to, but I don't need this object. In DbContext I added "HasOptional", why EF creates Ecwid object for me?

Answer 1

HasOptional means that EF must create new column which is nullable . IF you don't want EF automatically creates a new column in database, then just map this realtionship to existing column:

modelBuilder.Entity<Project>()
            .HasOptional(p => p.Ecwid)
            .WithRequired(p => p.Project)
            .Map(x => x.MapKey("Ecwid_ID"));

Or, if your FK column in Ecwid table, then change your mapping as:

modelBuilder.Entity<Ecwid>()
            .HasRequired(p => p.Project)
            .WithOptional(p => p.Ecwid);