c# - SQL 错误 : Introducing FOREIGN KEY constraint may cause cycles or multiple cascade paths. Entity Framework 核心

Question

我正在使用 SQL 并尝试使用 Entity Framework Core 添加迁移。我不确定如何解决这个问题。它用于将评论系统与用户和产品相关联。这在 SQLite 中有效。现在使用 SQL 服务器。我试图在简短的同时提供一切。如果需要，我可以提供更多。下面是我的代码，有人可以帮忙吗？

An error occurred while accessing the IWebHost on class 'Program'. Continuing without the application service provider. Error: Introducing FOREIGN KEY constraint 'FK_ProductReviews_AspNetUsers_ReviewerId' on table 'ProductReviews' may cause cycles or multiple cascade paths. Specify ON DELETE NO ACTION or ON UPDATE NO ACTION, or modify other FOREIGN KEY constraints. Could not create constraint or index. See previous errors.

我试过注释掉的代码。

            protected override void OnModelCreating(ModelBuilder builder)
        {
            base.OnModelCreating(builder);

    builder.Entity<MemberReview>()
                .HasKey(k => new { k.RevieweeId, k.ReviewerId });

            builder.Entity<MemberReview>().
                HasOne(u => u.Reviewer)
                .WithMany(u => u.ReviewedMembers);
                // .HasForeignKey(u => u.ReviewerId)
                // .OnDelete(DeleteBehavior.Restrict);

            builder.Entity<MemberReview>().
                HasOne(u => u.Reviewee)
                .WithMany(u => u.MemberReviews);
            // .HasForeignKey(u => u.RevieweeId)
            // .OnDelete(DeleteBehavior.Restrict);

            builder.Entity<ProductReview>()
                .HasKey(k => new { k.ReviewerId, k.ReviewedProductId });

            builder.Entity<ProductReview>().
                HasOne(u => u.ReviewedProduct)
                .WithMany(u => u.ProductReviews);
                //.HasForeignKey(u => u.ReviewedProductId)
                //.OnDelete(DeleteBehavior.Restrict);

            builder.Entity<ProductReview>().
                HasOne(u => u.Reviewer)
                .WithMany(u => u.ReviewedProducts);
                //.HasForeignKey(u => u.ReviewerId)
                //.OnDelete(DeleteBehavior.Restrict);
        }

        public class ProductReview
    {
        public Product ReviewedProduct { get; set; }
        public User Reviewer { get; set; }
        [Required]
        public int ReviewerId { get; set; }
        [Required]
        [MaxLength(30)]
        public string ReviewerUserName { get; set; }
        [Required]
        public int ReviewedProductId { get; set; }
        [Required]
        [MaxLength(35)]
        public string Title { get; set; }
        [Required]
        [MaxLength(420)]
        public string Review { get; set; }
        [Required]
        [MaxLength(2)]
        public int Rating { get; set; }
    }

        public class User : IdentityUser<int>
    {
        [Required]
        [MaxLength(12)]
        public string UserType { get; set; }
        [Required]
        public DateTime DateOfEstablishment { get; set; }
        [Required]
        [MaxLength(75)]
        public string KnownAs { get; set; }
        public DateTime Created { get; set; }
        public DateTime LastActive { get; set; }
        [MaxLength(420)]
        public string Description { get; set; }
        public ICollection<Photo> Photos { get; set; }
        public ICollection<Product> Products { get; set; }
        // REVIEW THING
        public ICollection<MemberReview> MemberReviews { get; set; }
        public ICollection<MemberReview> ReviewedMembers { get; set; }
        public ICollection<ProductReview> ReviewedProducts { get; set; }
        // *****
    }

        public class Product
    {
        public int Id { get; set; }
        [Required]
        [MaxLength(75)]
        public string Name { get; set; }
        [Required]
        [MaxLength(420)]
        public string Description { get; set; }
        public DateTime DateAdded { get; set; }
        public User User { get; set; }
        [Required]
        public int UserId { get; set; }
        // REVIEW THINGS
        public ICollection<ProductReview> ProductReviews { get; set; }
        // *****
    }

Answer 1

我刚试过这个:

protected override void OnModelCreating(ModelBuilder builder)
{
    base.OnModelCreating(builder);

    builder.Entity<MemberReview>()
        .HasKey(e => new { e.RevieweeId, e.ReviewerId });

    builder.Entity<ProductReview>()
        .HasKey(e => new { e.ReviewerId, e.ReviewedProductId });

    builder.Entity<MemberReview>()
        .HasOne<User>(e => e.Reviewer)
        .WithMany(e => e.MemberReviews)
        .HasForeignKey(e => e.ReviewerId)
        .OnDelete(DeleteBehavior.Restrict); ////////
                                                  //
    builder.Entity<MemberReview>()                //
        .HasOne<User>(e => e.Reviewee)            /// => only one of these two can be cascade
        .WithMany(e => e.ReviewedMembers)         //
        .HasForeignKey(e => e.RevieweeId)         //
        .OnDelete(DeleteBehavior.Restrict); ////////

    builder.Entity<ProductReview>()
        .HasOne<User>(e => e.Reviewer)
        .WithMany(e => e.ReviewedProducts)
        .HasForeignKey(e => e.ReviewerId)
        .OnDelete(DeleteBehavior.Restrict);
}

您没有提供 MemberReview 类，所以我创建了这个:

public class MemberReview
{
    public User Reviewer { get; set; }
    public int ReviewerId { get; set; }

    public User Reviewee { get; set; }
    public int RevieweeId { get; set; }
}

这是结果: