相关疑难解决方法(0)

我将这个Entity类与Entity Framework 5 Code First一起使用:

public class Survey
{
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int ID { get; set; }

    public string SurveyName { get; set; }

    [Required]
    public int ClientID { get; set; }

    [ForeignKey("ClientID")]
    public virtual Client Client { get; set; }
}

在我的Controller的Create方法中,我这样做:

    Survey entity = new Survey()
    {
        SurveyName = "Test Name",
        ClientID = 4
    };
    db.Surveys.Add(entity);
    db.SaveChanges();
    Client c1 = entity.Client;                    //Why is this null?
    Client c2 = db.Clients.Find(entity.ClientID); //But this isn't?

    string s2 = c2.ClientName;
    string s1 …