在 EF Core 中合并冲突

Question

我想更改项目中的模型和 tables。我现在有一些模型：Product、ProductType、ProductComposition、ProductSize、ShoppingCart。 Product有FK(ProductType, ProductTypeId)，其他有FK到Product(ProductId, Product)

我还有一个带有 Initialize 方法的 InitData.cs 文件，我在 table 中添加了一些东西，所以我有一些事情要做。但是问题来了：

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.

我不太清楚为什么会这样，可能是我FK的模型做错了什么？我刚学，所以有点难以理解。此外，我的 Guid cookie 生成方法也不知何故崩溃了。我看不出问题出在哪里，但是 cookie 是空的，我无法添加 GUID，即使它在我更改模型之前工作。我觉得这很奇怪，因为我根本没有改变 Startup.cs。

这是我的模型。

    {
        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，主要问题出现在哪里：

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();

        }
    }

我期望数据库结构可以通过 ProductTypeId 设置衣服类型，通过在 Size table 中使用布尔值设置尺码，并使用 int 设置 Composition？值。

Answer 1

您的 MERGE 语句试图插入一条在父 table 中没有相应记录的记录，因此出现错误。你需要确保

您需要先为子实体（如 ProductType table）播种，然后使用 context.SaveChanges() 保存数据 firstly.Then 您为 Product 播种具有现有 ProductTypeId 的实体并且还记得使用 context.SaveChanges().

此外，如果您想手动为 Key 提供一个值，您需要在该字段上添加以下属性：

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

否则会增加为1,2...

参考EF Core Generated Values

在 EF Core 中合并冲突

Merge conflict in EF Core

c#

sql

localdb

asp.net-core