EF核中的冲突合并

Question

我一直想在项目中改变我的模型和表格。我现在有一些模型:产品，ProductType，ProductComposition，ProductSize，ShoppingCart。产品有FK (ProductType，ProductTypeId)，其他产品有FK到Product (ProductId，Product)

另外，我有一个带有Initialize方法的InitData.cs文件，我在表中添加了一些内容，所以我有一些工作要做。但问题是：

Microsoft.EntityFrameworkCore.DbUpdateException: An error occurred while updating the entries. See the inner exception for details. ---> System.Data.SqlClient.SqlException: 
The MERGE statement conflicted with the FOREIGN KEY constraint "FK_Products_ProductTypes_ProductTypeId". The conflict occurred in database "clothesstoredb", table "dbo.Products", column 'Id'.
The statement has been terminated.

我不清楚为什么会发生这种事，也许我对FK的模特做错了什么？我只是在学习，所以有点难以理解。此外，我的Guid生成方法也以某种方式崩溃了。我不知道问题出在哪里，但是cookie是空的，我不能添加GUID，甚至在我更改模型之前它也能工作。我觉得这很奇怪，因为我根本没有改变Startup.cs。

这是我的模特。

    {
        public int Id { get; set; }
        public string Image { get; set; }
        public string BrandName { get; set; }
        public string Name { get; set; }       
        public string Description { get; set; }
        public string Material { get; set; }
        public int Price { get; set; }       

        public int ProductTypeId { get; set; }
        public ProductType ProductType { get; set; }
    }

    public class ProductType
    {
        public int Id { get; set; }
        public string Description { get; set; }
    } 

public class ProductComposition
    {
        public int Id { get; set; }
        public int? Cotton { get; set; }
        public int? Denim { get; set; }
        public int? Leather { get; set; }
        public int? Polyester { get; set; }
        public int? Nylon { get; set; }
        public int? Elastane { get; set; }

        public int ProductId { get; set; }
        public Product Product { get; set; }
    }

public class ProductSize
    {
        public int Id { get; set; }

        public bool S { get; set; }
        public bool M { get; set; }
        public bool L { get; set; }
        public bool XL { get; set; }
        public bool XXL { get; set; }

        public int ProductId { get; set; }
        public Product Product { get; set; }

    }

public class ShoppingCart
    {
        public int Id { get; set; }
        public string Guid{ get; set; }
        public int Quantity { get; set; }
        public int ProductId { get; set; }
        public Product Product { get; set; }
    }

这是我的InitData.cs，这里出现了主要问题：

public static class InitData
    {
        public static void Initialize(ClothesContext context)
        {
            if (!context.Products.Any())
            {
                context.Products.AddRange(
                   new Product
                   {
                       Id = 1,
                       BrandName = "Vans",
                       Name = "Лонгслив OTW RAGLAN",
                       Image = "https://a.lmcdn.ru/img600x866/V/A/VA984EMCRY32_1833129_1_v2.jpg",
                       Description = "Хлопковый лонгслив от Vans решен в контрастной бело-черной цветовой гамме. " +
                       "Детали: прилегающий крой, рукав 3/4, округлый вырез горловины, стильный принт на фронтальной стороне.",
                       Material = "Хлопок - 100%",
                       Price = 2151,
                       ProductTypeId = 3

                   },
                   new Product
                   {
                       BrandName = "United Colors of Benetton",
                       Name = "Рубашка",
                       Price = 2510,
                       Description = "Рубашка United Colors of Benetton выполнена из тонкого, приятного на ощупь материала. Модель приталенного кроя. " +
                       "Детали: отложной воротник, планка и манжеты на пуговицах, слегка удлиненная спинка.",
                       Image = "https://a.lmcdn.ru/img600x866/U/N/UN012EMVWY79_5145481_1_v4.jpg",
                       Material = "Хлопок - 68%, Нейлон - 28%, Эластан - 4%",
                       ProductTypeId = 4

                   },
                   new Product
                   {
                       BrandName = "Jordan",
                       Name = "Толстовка M J JUMPMAN FLEECE FZ",
                       Price = 5690,
                       Description = "Толстовка от спорт-бренда выполнена из хлопкового трикотажа. Модель прямого кроя. " +
                       "Детали: регулируемый капюшон, два кармана, манжеты и низ на резинки, застежка на молнию.",
                       Image = "https://a.lmcdn.ru/img600x866/J/O/JO025EMFNEV0_9024380_1_v1_2x.jpg",
                       Material = "Хлопок - 80%, Полиэстер - 20%",
                       ProductTypeId = 2
                   },
                   new Product
                   {
                       BrandName = "Burton Menswear London",
                       Name = "Футболка",
                       Price = 1430,
                       Description = "Футболка из 100% хлопка.",
                       Image = "https://a.lmcdn.ru/img600x866/B/U/BU014EMFIHX0_8767196_1_v1.jpg",
                       Material = "Хлопок - 100%",
                       ProductTypeId = 1
                   }

                );


            }

            if (!context.ProductTypes.Any())
            {
                context.ProductTypes.AddRange(
                    new ProductType {                        
                        Description = "Футболки"
                    },
                    new ProductType
                    {                        
                        Description = "Худи"
                    },
                    new ProductType
                    {                        
                        Description = "Лонгсливы"
                    },
                    new ProductType
                    {

                        Description = "Рубашки"
                    }            
                    );

            }
            if (!context.ProductSizes.Any())
            {
                context.ProductSizes.AddRange(
                    new ProductSize
                    {
                        ProductId = 1,
                        XL = false,
                        L = true,
                        M = false,
                        S = false,
                        XXL = true
                    },
                    new ProductSize
                    {
                        ProductId = 2,
                        XL = true,
                        L = true,
                        M = true,
                        S = false,
                        XXL = true
                    },
                    new ProductSize
                    {
                        ProductId = 3,
                        XL = true,
                        L = false,
                        M = false,
                        S = false,
                        XXL = true
                    },
                    new ProductSize
                    {
                        ProductId = 4,
                        XL = false,
                        L = true,
                        M = false,
                        S = false,
                        XXL = true
                    }

                    );


            }
            if (!context.ProductCompositions.Any())
            {
                context.ProductCompositions.AddRange(
                    new ProductComposition
                    {
                        ProductId = 1,
                        Cotton = 100
                    },
                    new ProductComposition
                    {
                        ProductId = 2,
                        Cotton = 68,
                        Nylon = 28,
                        Elastane = 4
                    },
                    new ProductComposition
                    {
                        ProductId = 3,
                        Cotton = 80,
                        Polyester = 20
                    },
                    new ProductComposition
                    {
                        ProductId = 4,
                        Cotton = 100
                    }

                );


            }
            context.SaveChanges();

        }
    }

我期望DB结构，可以通过ProductTypeId设置衣服类型，在尺寸表中使用布尔值来设置大小，用int来组合？值。

Answer 1

您的MERGE语句试图插入在父表中没有相应记录的记录，因此出现错误。你得确保

首先，您需要为您的子实体(如ProductType表)添加种子，并使用context.SaveChanges()保存数据-- firstly.Then --您用现有的ProductTypeId为Product实体添加种子，并记住使用context.SaveChanges()。

此外，如果您希望手动为Key提供一个值，则需要在字段中添加以下属性：

[Key]
[DatabaseGenerated(DatabaseGeneratedOption.None)]
public int Id { get; set; }

否则它会增加到1，2.

请参阅EF核心生成值