实体框架6表具有许多外键，每个外键指向不同的表

Question

我有国家，城市，地区和“帐户地址”表。

我想在“帐户地址”中创建指向国家，城市，地区表的外键列。

我有这段代码，但是在创建数据库时抛出错误

无法将属性\\ u0027Account_Id \\ u0027配置为导航属性。 该属性必须是有效的实体类型，并且该属性应具有非抽象的getter和setter。 对于集合属性，类型必须实现

After New Edit

public class Cities
{
    [Key]
    public int City_Id { get; set; }
    public string City_name { get; set; }
    public int Country_Id { get; set; }

    [ForeignKey("Country_Id")]
    public Countries countries { get; set; }
}

public class Region
{
    [Key]
    public int Region_Id { get; set; }
    public string Region_name { get; set; }
    public int City_Id { get; set; }

    [ForeignKey("City_Id")]
    public Countries countries { get; set; }
}

public class Accounts
{
    [Key]
    public int Account_Id { get; set; }
    public string Fullname { get; set; }
    public string Email { get; set; }
    public string password { get; set; }
    public int Cell_phone { get; set; }
    public string Role { get; set; }
    public int? estate_office_Id { get; set; }

    [ForeignKey("estate_office_Id")]
    public Estate_office estate_office { get; set; }

    public List<Ads> ads { get; set; }
}

public class Account_address
{
    [Key]
    public int Id { get; set; }

    [ForeignKey("Account_Id"), Column(Order = 0)]
    public int Account_Id { get; set; }

    [ForeignKey("Country_Id"), Column(Order = 1)]
    public int Country_Id { get; set; }

    [ForeignKey("City_Id"), Column(Order = 2)]
    public int City_Id { get; set; }

    [ForeignKey("Region_Id"), Column(Order = 3)]
    public int Region_Id { get; set; }

    public Accounts accounts { get; set; }
    public Countries countries { get; set; }
    public Cities cities { get; set; }
    public Region region { get; set; }
}

Answer 1

您需要按如下所示在Account_address上定义public属性。然后，只有EF知道如何正确映射这些导航属性。

  public class Account_address
   {
    ......
    ......


    public  Accounts accounts { get; set; } //like this
    public  Countries countries { get; set; } //like this
    public  Cities cities { get; set; } //like this
    public  Region region { get; set; } //like this
  }

更新：

因此，您没有对类使用单数命名约定，就遇到了这个问题。要么必须将类的名称更改为单数，要么需要更改如下所示的导航属性名称。您必须对所有这里仅显示了与Accounts类相关的导航属性。

    [ForeignKey("Accounts_Id"), Column(Order = 0)]
    public int Accounts_Id { get; set; }

我的建议是遵循基本的命名约定 。然后，您可以避免出现许多上述奇怪的错误。