c# - 该属性必须是有效的实体类型，并且该属性应该具有非抽象 getter 和 setter。 Entity Framework

Question

这个问题已经有答案了:

Understanding ForeignKey attribute in entity framework code first (3 个回答)

已关闭 2 年前。

我在 Entity Framework 中首先从代码创建数据库时遇到问题。我有以下三个类 1 Person、2 PersonAddress、3 PersonEmploymentHistory 如下所示。

namespace DataAccess.Models
{
[Table("Profile")]
public class Person
{
    [Key]
    public int UserId { get; set; }

    [Required(ErrorMessage = "Firstname is required")]
    public string PersonFirstName { get; set; }

    [Required(ErrorMessage = "Surname is required")]
    public string PersonSurname { get; set; }

    [Required(ErrorMessage = "Email is required")]
    [DataType(DataType.EmailAddress)]
    public string PersonEmail { get; set; }
    public int Age { get; set; }

    [Required(ErrorMessage = "Contact Number required")]
    public Int64 PersonNumber { get; set; }

    public bool IsActive { get; set; }

    [ForeignKey("AddressDetails")]
    public int AddressId { get; set; }
    public virtual PersonAddress AddressDetails { get; set; }

    [ForeignKey("EmploymentHistory")]
    public int EmployerId { get; set; }
    public virtual PersonEmploymentHistory EmploymentHistory { get; set; }

}
}

PersonAddress 类

namespace DataAccess.Models
{
[Table("AddressDetails")]
public class PersonAddress
{
    [Key]
    public int AddressId { get; set; }

    [ForeignKey("UserId")]
    public int UserId { get; set; }

    [Required(ErrorMessage = "Address Line 1 required")]
    public string AddressLine1 { get; set; }

    [Required(ErrorMessage = "Address Line 2 required")]
    public string AddressLine2 { get; set; }

    [Required(ErrorMessage = "Postcode required")]
    [DataType(DataType.PostalCode)]
    public string PostCode { get; set; }
}
}

个人就业历史

namespace DataAccess.Models
{
[Table("EmploymentHistory")]
public class PersonEmploymentHistory
{
    [Key]
    public int EmployerId { get; set; }
    public string EmployerName { get; set; }
    public decimal EmployeeSalary { get; set; }
    public DateTime StartDate { get; set; }
    public DateTime EndDate { get; set; }
    public string ReasonForLeaving { get; set; }

    [ForeignKey("UserId")]
    public int UserId { get; set; }
}
}

这是我的 Context 类

 public class Context : DbContext
{
    public Context()
        : base("DefaultConnection")
    {
        Database.SetInitializer<Context>(new CreateDatabaseIfNotExists<Context>());
    }

    public DbSet<Person> Person { get; set; }
    public DbSet<PersonAddress> PersonAddress { get; set; }
    public DbSet<PersonEmploymentHistory> PersonEmployment { get; set; }

}

现在我在创建外键等时遵循了教程，但是当我运行我的项目并尝试将数据插入人员表时，我收到以下错误

属性“UserId”无法配置为导航属性。该属性必须是有效的实体类型，并且该属性应该具有非抽象 getter 和 setter。对于集合属性，类型必须实现 ICollection，其中 T 是有效的实体类型。

Answer 1

我也是先学习代码。我使用的是 Fluent API，所以我对注释没有那么丰富的经验。我认为你做外键的方式是错误的。我认为它们应该看起来像:

public int UserId { get; set; }
[ForeignKey("UserId")]
public virtual Person User{ get; set; }

不同之处在于您有一个 FK 类型的变量并对其进行注释。您还可以查找 Fluent API。

参见http://www.codeproject.com/Articles/319366/EF-Code-First-Add-a-Foreign-Key-relationship