使用IBM DB2调用SaveChangesAsync（）时，EF Core 2.1.1“ DbUpdateConcurrencyException”

Question

我正在尝试将数据库提供程序从SqlServer切换到Db2。 现在我遇到的问题是，当我打电话时：

await SaveChangesAsync()

EF删除错误

  

DbUpdateConcurrencyException：数据库操作预期影响1行，但实际上影响0行。自加载实体以来，数据可能已被修改或删除。

同步操作正常。

        await context.SaveChangesAsync(); // doesn't work

        context.SaveChanges(); // works

最简单的方法是使其同步，但是我还使用了完全不熟悉的asp.net核心标识。

我不再有解决此问题的想法，也许是错误。以为它可能像this，因为我之前使用过EF Core 2.0，但在成功升级到2.1.1之后才使用。错误仍然消失。

这可能是提供商的问题吗？使用最新版本的IBM.Db2 Provider。

我公司的通用数据库是db2，这就是为什么我必须更改提供程序。

更新：
该问题似乎仅在我尝试执行INSERT时才会发生。

在Startup.cs中

services.AddDbContext<MyDbContext>(options => {
options.UseLoggerFactory(Config.DbLogger);

options.UseDb2(Configuration.GetConnectionString("DB2Connection"), config =>
{
    config.SetServerInfo(IBM.EntityFrameworkCore.Storage.Internal.IBMDBServerType.LUW, IBM.EntityFrameworkCore.Storage.Internal.IBMDBServerVersion.LUW_11_01_2020);
});
});

MyContext.cs

public class MyContext : DbContext
{
    public DbSet<Event> Events { get; set; }
    protected override void OnModelCreating(ModelBuilder builder)
    {
        builder.Entity<Event>().ToTable("Events");
    }
}

MyController.cs

    public class MyController : Controller
    {
        private readonly MyContext context;
        public MyController(MyContext _context)
        {
            context = _context;
        }

        [HttpPost]
        public async Task<IActionResult> Create()
        {
            var _event = new Event { ID = Guid.NewGuid().ToString(), UserID = "adwadawdawdaw", TargetID = "1", Target = "todo", TimeStamp = DateTime.Now };
            await context.Events.AddAsync(_event);
            await context.SaveChangesAsync();   // <- Fails with "DbUpdateConcurrencyException"
            // context.SaveChanges(); // <- works!

            return Ok();
        }
        [HttpPut]
        public async Task<IActionResult> Update()
        {
            var _event = context.Events.FirstOrDefault();
            _event.TargetID = "2";
            await context.SaveChangesAsync(); // <- works!
            return Ok();
        }
        [HttpDelete]
        public async Task<IActionResult> Delete()
        {
            var _event = context.Events.FirstOrDefault();
            context.Events.Remove(_event);
            await context.SaveChangesAsync();   // <- works
            return Ok();
        }
    }

连接字符串

  

服务器=本地主机：50000;数据库= db1; UID =用户; PWD =密码; CurrentSchema =待办事项;

DB2版本11.1

表：

错误消息：

DbUpdateConcurrencyException: Database operation expected to affect 1 row(s) but actually affected 0 row(s). Data may have been modified or deleted since entities were loaded. See http://go.microsoft.com/fwlink/?LinkId=527962 for information on understanding and handling optimistic concurrency exceptions.
Microsoft.EntityFrameworkCore.Update.AffectedCountModificationCommandBatch.ThrowAggregateUpdateConcurrencyException(int commandIndex, int expectedRowsAffected, int rowsAffected)
Microsoft.EntityFrameworkCore.Update.AffectedCountModificationCommandBatch.ConsumeResultSetWithoutPropagationAsync(int commandIndex, RelationalDataReader reader, CancellationToken cancellationToken)
Microsoft.EntityFrameworkCore.Update.AffectedCountModificationCommandBatch.ConsumeAsync(RelationalDataReader reader, CancellationToken cancellationToken)
Microsoft.EntityFrameworkCore.Update.ReaderModificationCommandBatch.ExecuteAsync(IRelationalConnection connection, CancellationToken cancellationToken)
Microsoft.EntityFrameworkCore.Update.Internal.BatchExecutor.ExecuteAsync(DbContext _, ValueTuple<IEnumerable<ModificationCommandBatch>, IRelationalConnection> parameters, CancellationToken cancellationToken)
Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.SaveChangesAsync(IReadOnlyList<InternalEntityEntry> entriesToSave, CancellationToken cancellationToken)
Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.SaveChangesAsync(bool acceptAllChangesOnSuccess, CancellationToken cancellationToken)
Microsoft.EntityFrameworkCore.DbContext.SaveChangesAsync(bool acceptAllChangesOnSuccess, CancellationToken cancellationToken)

Answer 1

尚不支持

SaveChangesAsync()，请改用 SaveChanges()。我知道这似乎很疯狂，可悲的事实。