EF 6代码优先错误：EntityType没有定义键

Question

I have defined a class that holds the createby,createdate,modifyby and modifydate properties which is inherited by other classes { so that i don't have to create the field in all the entities that have those field}. My code is

public class SMSModelBaseClass
{

    [Required]
    [StringLength(50)]
    [Column(TypeName ="varchar")]
    [ScaffoldColumn(false)]
    public string CreateById { get; set; }

    [Required]
    [ScaffoldColumn(false)]
    public DateTime CreateDate { get; set; }

    [Required]
    [StringLength(50)]
    [ScaffoldColumn(false)]
    [Column(TypeName = "varchar")]
    public string ModifyById { get; set; }

    [Required]
    [ScaffoldColumn(false)]
    public DateTime ModifyDate { get; set; }

    [ForeignKey("CreateById")]
    public virtual ApplicationUser CreateBy { get; set; }

    [ForeignKey("ModifyById")]
    public virtual ApplicationUser ModifyBy { get; set; }

}

Am getting the subject error. I know i could introduce a primary key for the same but it will get inherited by the other classes, something that i dont want.

Is it possible either using fluent api or data annotations to bypass this error?

Answer 1

With EntityFramework, each entity needs a key property.

Typically this is an Id column.
It could be a composite key, but given your model, I would suggest an Id property on SMSModelBaseClass

As a side note, I believe SMSModelBaseClass should also be abstract if you are using it as a base class, and not instantiating it directly