在我使用 C# 编写的新 WPF 项目中,我想尝试使用 Entity Framework Core与我的 SQL Server 数据库交互。
每次我尝试将模型添加到我的上下文中时,我都会收到以下错误
Cannot insert explicit value for identity column in table 'Orders' when IDENTITY_INSERT is set to OFF.
我正在使用 Repository
和 UnitOfWork
包装 Entity Framework Core 方法来执行所需的工作。
但在最简单的情况下,我正在执行以下代码
var order = new Order();
order.Title = "some";
....
Context.Orders.Add(order);
Context.SaveChanges();
这是我的模型
public class Order
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public Int64 Id { get; set; }
public string Status { get; set; }
public int? CustomerId { get; set; }
public DateTime? Birthdate { get; set; }
public int UtcOffset { get; set; }\
public DateTime CreatedAt { get; set; }
public DateTime? UpdatedAt { get; set; }
public int? UpdatedBy { get; set; }
[ForeignKey(nameof(Creator))]
public int CreatedBy { get; set; }
public Order()
{
CreatedAt = DateTime.UtcNow;
}
public virtual User Creator { get; set; }
public virtual Customer Customer { get; set; }
}
是什么导致了这个问题?
已更新
这是我的表是如何创建的
CREATE TABLE [dbo].[Orders](
[Id] [bigint] IDENTITY(1,1) NOT NULL,
[Status] [varchar](50) NOT NULL,
[CustomerId] [int] NULL,
[Birthdate] [datetime] NULL,
[CreatedBy] [int] NOT NULL,
[CreatedAt] [datetime] NOT NULL,
[UpdatedBy] [int] NULL,
[UpdatedAt] [datetime] NULL,
[UtcOffset] [int] NOT NULL,
CONSTRAINT [PK_Orders] PRIMARY KEY CLUSTERED
(
[Id] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
下面是创建Order
模型的方法
public Order Create(int? customerId, DateTime? birthdate)
{
var order = new Order();
order.CustomerId = customerId;
order.Birthdate = birthdate;
order.Status = OrderStatus.Sold.ToString();
order.CreatedBy = Passport.Identity.Id;
var updatedOrder = Orders.Add(order);
Orders.Save();
return updatedOrder;
}
这是我的存储库实现
public class EntityRepository<TEntity, TKeyType> : IRepository<TEntity, TKeyType>
where TEntity : class
where TKeyType : struct
{
protected readonly DbContext Context;
protected readonly DbSet<TEntity> DbSet;
public EntityRepository(DbContext context)
{
Context = context;
DbSet = context.Set<TEntity>();
}
public TEntity Get(TKeyType id)
{
return DbSet.Find(id);
}
public IEnumerable<TEntity> GetAll()
{
return DbSet.ToList();
}
public bool Any(Expression<Func<TEntity, bool>> predicate)
{
return DbSet.Any(predicate);
}
public IQueryable<TEntity> Find(Expression<Func<TEntity, bool>> predicate)
{
return DbSet.Where(predicate);
}
public TEntity SingleOrDefault(Expression<Func<TEntity, bool>> predicate)
{
return DbSet.SingleOrDefault(predicate);
}
public virtual TEntity Add(TEntity entity)
{
DbSet.Add(entity);
return entity;
}
public virtual IEnumerable<TEntity> AddRange(IEnumerable<TEntity> entities)
{
DbSet.AddRange(entities);
return entities;
}
public void Remove(TEntity entity)
{
DbSet.Remove(entity);
}
public void RemoveRange(IEnumerable<TEntity> entities)
{
DbSet.RemoveRange(entities);
}
public void Update(TEntity entity)
{
DbSet.Attach(entity);
var record = Context.Entry(entity);
record.State = EntityState.Modified;
}
public IQueryable<TEntity> Query()
{
return DbSet;
}
public void Save()
{
Context.SaveChanges();
}
}
public class EntityRepository<TEntity> : EntityRepository<TEntity, int>
where TEntity : class
{
public EntityRepository(DbContext context)
: base(context)
{
}
}
此外,这个问题在 Entity Framework error: Cannot insert explicit value for identity column in table 上不是重复的因为我正在使用 [DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
装饰我的 Id 属性。此外,我使用的是数据库优先方法,所以我使用 MSSMS 手动创建了数据库
最佳答案
在我的例子中,我必须将 entity.Property(e => e.TranId).ValueGeneratedOnAdd();
添加到我的上下文文件中。
modelBuilder.Entity<PersonalTrades>(entity =>
{
entity.Property(e => e.TranId).ValueGeneratedOnAdd();
}
我没有从 Automapper 更新身份字段 (TranId)。最后,上述更改对我有用,正如名称指定的那样,它在插入记录时为身份字段生成值。
关于c# - 如何使用 Entity Framework Core 将属性设置为 "Identity"或自动递增的列?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/50440713/