[英]Entity Framework Core: Cannot insert explicit value for identity column in table
[英]Cannot insert explicit value for identity column in table Entity Framework
我有一个在我的数据库中存储股票的表单,当我输入一个股票时,它会保留信息,当我尝试添加另一只股票时,我得到一个异常“无法为表中的标识列插入显式值”
在我的 model 中,我声明了我的STOCKID
属性,并在我的 T-SQL 中将其设置为IDENTITY(1,1)
。
在我的 model 中,我添加了[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
但这没有帮助
有什么建议么?
Model
public class Stock
{
#region Day 1's
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int Id { get; set; }
T-SQL
CREATE TABLE [dbo].[LowFloatStocks]
(
[Id] INT IDENTITY (1, 1) NOT NULL,
[Date] DATE NOT NULL,
[Ticker] NVARCHAR (4) NOT NULL,
[PreviousClose] DECIMAL (4, 2) DEFAULT ((4.00)) NOT NULL,
[PM_OpeningPrice] DECIMAL (18, 2) DEFAULT ((3)) NOT NULL,
[OpeningPrice] DECIMAL (18, 2) NOT NULL,
[PMFadePercent] AS (ROUND(([OpeningPrice] - [PM_OpeningPrice]) / [PM_OpeningPrice], (4)) * (100.0)) PERSISTED NOT NULL,
[GainPercent] AS (ROUND(([High] - [OpeningPrice]) / [OpeningPrice], (4)) * (100.0)) PERSISTED NOT NULL,
[GapPercent] AS (ROUND(([OpeningPrice] - [PreviousClose]) / [PreviousClose], (4)) * (100.0)) PERSISTED NOT NULL,
[Spike] DECIMAL (18, 2) NOT NULL,
[1stSpike%] AS (ROUND(([Spike] - [OpeningPrice]) / [OpeningPrice], (4)) * (100.0)) PERSISTED NOT NULL,
[High] DECIMAL (18, 2) NOT NULL,
[HighPercent] AS (ROUND(([High] - [PreviousClose]) / [PreviousClose], (4)) * (100.0)) PERSISTED NOT NULL,
[Low] DECIMAL (18, 2) NOT NULL,
[LowPercent] AS (ROUND(([Low] - [PreviousClose]) / [PreviousClose], (4)) * (100.0)) PERSISTED NOT NULL,
[Close] DECIMAL (18, 2) DEFAULT ((4)) NOT NULL,
[ClosePercent] AS (round(([Close]-[PreviousClose])/[PreviousClose],(4))*(100.0)) PERSISTED NOT NULL,
[ClosevHigh] AS (round(([High]-[Close])/[Close], (4))*(100)) PERSISTED NOT NULL,
[ClosevOpen] AS (round(([OpeningPrice]-[Close])/[OpeningPrice],(4))*(100.0)) PERSISTED NOT NULL,
[CloseLessEqualToOpen] AS (CONVERT([nchar](3),case when [Close]<=[OpeningPrice] then 'Yes' else 'No' end)) PERSISTED NOT NULL,
[CloseRed] AS (CONVERT([nchar](3),case when [Close]<[OpeningPrice] then 'Yes' else 'No' end)) PERSISTED NOT NULL,
[Catalyst] NVARCHAR (50) NOT NULL,
[Float] DECIMAL (18, 3) NOT NULL,
[Dilution] NCHAR (3) NOT NULL,
PRIMARY KEY CLUSTERED ([Id] ASC)
);
添加库存方法
public ICommand AddCommand => _addCommand ?? (_addCommand = new RelayCommand(param => this.AddStock()));
#endregion
#region Actions
private void AddStock()
{
using (var stocks = new AppDbContext())
{
stocks.LowFloatStocks.Add(stock);
stocks.SaveChanges();
Stocks = stocks.LowFloatStocks.ToList();
Clear();
}
}
如果您想自己创建密钥,则应使用[DatabaseGenerated(DatabaseGeneratedOption.None)]
。 [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
意味着您让数据库处理主键的创建。 这通常是最好的选项,因为您的软件的两个实例尝试创建相同的主键将导致错误。 这是一个不太可能的场景,但仍然:让数据库创建主键。 当您使用 Database First 时,您没有在不更新数据库的情况下更改DatabaseGeneratedOption
的选项。 如果您从数据库创建了 Code First Model,您可以选择更改DatabaseGeneratedOption
,创建新的迁移和更新数据库。 但这可能是不可取的,因为实体框架可能会删除整个表并重新创建它。
请显示创建在stocks.LowFloatStocks.Add(stock);
. 您是否为Id
分配了一个值? 如果是这样,尽量不要那样做。
否则,请尝试 @viveknuna 在评论中建议的解决方案:
stock.Id = 0;
stocks.LowFloatStocks.Add(stock);
stocks.SaveChanges();
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