'FK_Ratings_Users_UserId' on table 'Ratings' 可能会导致循环或多个级联路径

Question

我正在 .NET EFCore 中尝试通过以下实体进行以下 Code-First 迁移

用户

[Table("Users")]
public class User
{
    [Key]
    public int Id { get; set; }

    [Required]
    [MaxLength(100)]
    public string FirstName { get; set; }

    [Required]
    [MaxLength(100)]
    public string LastName { get; set; }

    [Required]
    [MaxLength(250)]
    public string Email { get; set; }

    [Required]
    [MinLength(8), MaxLength(16)]
    public string Password { get; set; }

    [Required]
    [MinLength(6), MaxLength(15)]
    public string Phone { get; set; }

    public ICollection<Apartment> Apartments { get; set; }

    public ICollection<Rating> Ratings { get; set; }
}

公寓

[Table("Apartments")]
public class Apartment
{
    [Key]
    public int Id { get; set; }

    [Required]
    [MinLength(24), MaxLength(100)]
    public string Title { get; set; }

    [Required]
    [MinLength(24), MaxLength(250)]
    public string Address { get; set; }

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

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

    public User User {get; set;}

    public ICollection<Rating> Ratings { get; set; }

    public ICollection<AptCateg> AptsCategs { get; set; }
}

评分

[Table("Ratings")]
public class Rating
{
    [Key]
    public int Id { get; set; }

    public int Value { get; set; }

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

    public Apartment Apartment { get; set; }

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

    public User User { get; set; }
}

我使用命令 dotnet ef migrations add InitialDatabase 但是当我尝试使用 dotnet ef database update 它会在 cmd 中抛出以下错误，如标题

'FK_Ratings_Users_UserId' on table 'Ratings' may cause cycles or multiple cascade paths

我尝试在 here the modelBuilder's Cascade behavior but it doesn't work because I am getting the same error. I have also tried doing the answer from here 的 EFCore 教程中添加，但是即使尝试安装 [=19]，HasRequired 的实现也不起作用=].

我了解到正在进行的通告 thingy 存在问题。根据我的直觉，该程序不知道在删除用户的情况下该怎么做，是否删除其评级和公寓或类似的东西，这就是它以这种方式行事的原因，但我无法修复问题。

我的问题是，我无法创建我的数据库，因此无法继续处理该项目，我该如何解决这个问题。

谢谢！

Answer 1

您将 User 和 Apartment 添加到 Ratings 导致循环引用实体。 User 和 Apartment 实体已经与 Ratings 集合建立了一对多关系。

'FK_Ratings_Users_UserId' on table 'Ratings' may cause cycles or multiple cascade paths

Ratings 实体应如下所示：

[Table("Ratings")]
public class Rating
{
    [Key]
    public int Id { get; set; }

    public int Value { get; set; }
}

Answer 2

您必须在其中一个表中将用户关系设为可选，例如：

public int? UserId { get; set; }

使属性类型可为 null 告诉 EF 这里不需要级联删除。

'FK_Ratings_Users_UserId' on table 'Ratings' 可能会导致循环或多个级联路径

'FK_Ratings_Users_UserId' on table 'Ratings' may cause cycles or multiple cascade paths

foreign-keys

entity-framework-migrations

asp.net-core

用户

公寓

评分