“引入 FOREIGN KEY 约束”错误

Question

我有 3 个主要实体：类别、子类别、产品：

public class Product
{
    public Product()
    {
        Photos = new List<Photo>();
        Comments = new List<Comment>();
        Colors = new List<ProductColor>();
        Attributes = new List<ProductAttributes>();
    }

    public int Id { get; set; }
    public string ProductName { get; set; }
    public string BrandName { get; set; }
    public string SellerName { get; set; }
    public decimal Price { get; set; }
    public bool OnSale { get; set; }
    public int SalePercantage { get; set; }
    public DateTime DateAdded { get; set; }
    public int UnitsInStock { get; set; }

    public string MainImageUrl 
    { 
        get 
        {
            return Photos.Count > 0 ? Photos[0].PhotoPath : "https://dummyimage.com/600x600/e0d0e0/ffffff.png";
        }
    }

    public decimal ShownPrice 
    {
        get 
        {
            if (OnSale) 
            {
                return SalePrice; 
            }
            else 
            {  
                return Price; 
            }
        } 
    }

    public decimal SalePrice 
    {
        get 
        {
            return (decimal)((decimal)Price - ((decimal)Price * ((decimal)SalePercantage / (decimal)100)));
        }
    }

    public bool IsNewBrand 
    {
        get 
        {
            return DateTime.Now.AddDays(-3) <= DateAdded;
        } 
    }

    public int SubCategoryId { get; set; }
    public SubCategory SubCategory { get; set; }
    public List<Photo> Photos { get; set; }
    public List<Comment> Comments { get; set; }
    public List<ProductColor> Colors { get; set; }
    public List<ProductAttributes> Attributes { get; set; }

    public List<ProductCategory> ProductCategories { get; set; }
    public List<ProductProductSize> ProductSizes { get; set; }
}

public class Category
{
    public int Id { get; set; }
    public string CategoryName { get; set; }

    public List<ProductCategory> ProductCategories { get; set; }
    public List<SubCategory> SubCategories { get; set; }
}

public class SubCategory
{
    public int Id { get; set; }
    public string Name { get; set; }

    public List<Product> Products { get; set; }
    public int CategoryId { get; set; }
    public Category Category { get; set; }
}

在我的DbContext 中，我定义了我的关系：

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

        modelBuilder.Entity<ProductCategory>().HasKey(p => new { p.CategoryId, p.ProductId });
        modelBuilder.Entity<ProductCategory>().HasOne(p => p.Product).WithMany(d => d.ProductCategories).HasForeignKey(p => p.ProductId);
        modelBuilder.Entity<ProductCategory>().HasOne(p => p.Category).WithMany(d => d.ProductCategories).HasForeignKey(p => p.CategoryId);
        modelBuilder.Entity<SubCategory>().HasOne(p => p.Category).WithMany(d => d.SubCategories).HasForeignKey(p => p.CategoryId);
        modelBuilder.Entity<Product>().HasOne(d => d.SubCategory).WithMany(p => p.Products).HasForeignKey(d => d.SubCategoryId);
}

当我尝试从 PowerShell 迁移我的数据库时，我收到了以下错误：

在表“ProductCategory”上引入 FOREIGN KEY 约束“FK_ProductCategory_Products_ProductId”可能会导致循环或多个级联路径。指定 ON DELETE NO ACTION 或 ON UPDATE NO ACTION，或修改其他 FOREIGN KEY 约束。
无法创建约束或索引。查看以前的错误。

我无法识别这里的问题，我做错了什么？

我的ProductCategory 实体不应该有HasOne.WithMany 代码或类似的东西吗？

我几乎尝试了所有方法，但仍然找不到解决方案。

Answer 1

在您的ProductCategory Fluent API 配置中指定.OnDelete(DeleteBehavior.Restrict)，如下所示：

modelBuilder.Entity<ProductCategory>()
            .HasOne(p => p.Product)
            .WithMany(d => d.ProductCategories)
            .HasForeignKey(p => p.ProductId)
            .OnDelete(DeleteBehavior.Restrict); // <-- Here it is


modelBuilder.Entity<ProductCategory>()
            .HasOne(p => p.Category)
            .WithMany(d => d.ProductCategories)
            .HasForeignKey(p => p.CategoryId)
            .OnDelete(DeleteBehavior.Restrict); // <-- Here it is

现在再次生成迁移并更新数据库。