为什么“ ID = 0”？当我尝试在数据库中插入字段为主键时？ [英] Why "ID = 0" when I try to insert in database while the field is primary key?

问题描述

我试图在数据库的 BookInfo 表中插入（创建）一本书，但出现此错误：

I am trying to insert (create) a book in the BookInfo table in database but I get this error:

处理请求时发生未处理的异常。
SqlException：INSERT语句与FOREIGN KEY约束 FK_Book_Categories_BookInfo_BookID冲突。冲突发生在数据库 MyBookShopDB，表 dbo.BookInfo，列 BookID中。

An unhandled exception occurred while processing the request. SqlException: The INSERT statement conflicted with the FOREIGN KEY constraint "FK_Book_Categories_BookInfo_BookID". The conflict occurred in database "MyBookShopDB", table "dbo.BookInfo", column 'BookID'.

我有具有多对多关系的BookInfo 和类别。

我正在使用视图模型做这份工作。我认为问题在于，当我跟踪 Create 操作方法时，我会看到 BookID 为 0 ;

And I am using a view model to do the job. I think the problem is that when I trace my Create action method, then I see that the BookID is "0"

但是 BookID 被定义为自动增量主键，我不知道为什么它仍为 0。当我尝试创建一本书或将一本书插入数据库时​​......

But BookID is defined as an auto-increment primary key and I do not know why it is still "0" when I try to create or insert a book into the database....

有人知道我该怎么做才能解决这个问题？

Does anyone know what should I do to solve this problem?

谢谢！

public async Task<IActionResult> Create(BooksCreateViewModel ViewModel)
{
    if (ModelState.IsValid)
    {
        Book book = new Book()
                        {
                            ISBN = ViewModel.ISBN,
                            Stock = ViewModel.Stock,
                            Price = ViewModel.Price,
                            Title = ViewModel.Title,
                        };

        await _context.Books.AddAsync(book);
    }
}

这是BookInfo类：

Here is the BookInfo Class:

  [Table("BookInfo")]
public class Book
{
    [Key]
    public int BookID { get; set; }

    [Required]
    public string Title { get; set; }
    public string Summary { get; set; }
    public int Price { get; set; }
    public int Stock { get; set; }
}

这是迁移类：

migrationBuilder.CreateTable(
            name: "BookInfo",
            columns: table => new
            {
                BookID = table.Column<int>(nullable: false)
                    .Annotation("SqlServer:Identity", "1, 1"),
                Title = table.Column<string>(nullable: false),
                Summary = table.Column<string>(nullable: true),
                Price = table.Column<int>(nullable: false),
                Stock = table.Column<int>(nullable: false),
            },

SQL

ALTER TABLE [dbo].[Book_Categories] ADD  CONSTRAINT [PK_Book_Categories] PRIMARY KEY CLUSTERED ([BookID] ASC,[CategoryID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]

推荐答案

在Book实体中，您是否向Book.ID添加了装饰器以通知Entity Framework允许服务器分配值？

In the Book Entity have you added a decorator to Book.ID to inform Entity Framework to allow the Server to assign the value?

类似这样的事情：

public class Book
{
    public Book() { }

    [DatabaseGenerated(DatabaseGeneratedOption.Identity), Key]
    public int ID { get; set; }
    public string ISBN { get; set; }
    public string Stock { get; set; }
    public string Price { get; set; }
    public string Title { get; set; } 
}

有关实体框架核心数据库注解的信息

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