为什么当发生两个并发更改时,RowVersion属性不引发乐观并发异常?

我有以下实体,

 public class PatientRegistry : BaseEntity {

        [Key, DatabaseGenerated(DatabaseGeneratedOption.None)]
        [Display(Name = "Patient File Number")]
        public long PatientFileId { get; set; }
        public virtual ICollection<PartnerRegistry> Partners { get; set; }
        public string UserId { get; set; }
        public string AliasName { get; set; }

        public DateTime? DateNow { get; set; }
        public virtual ApplicationUser User { get; set; }

    }

基本实体是,

 public class BaseEntity : ISoftDelete {
        public bool IsDeleted { get; set; }

        [Timestamp]
        public byte[] RowVersion { get; set; }
    }

RowVersion 属性和我使用fluent API将其配置为RowVersion。我使用存储库模式,这就是我在上下文中加载实体的方式,

 public async Task<PatientRegistry> GetPatient(long Id, bool isPartners = true, bool isUser = true) {
            if (isPartners && !isUser)
              return await context.PatientsRegistry
                .IgnoreQueryFilters()
                .Include(pt => pt.Partners)
                .Include(pt => pt.User)
                .Include(pt => pt.User.Gender)
                .Include(pt => pt.User.Nationality)
                .Include(pt => pt.User.Occupation)
                .Include(pt => pt.User.Ethnicity)
                .Include(pt => pt.User.MaritalStatus)
                .Include(pt => pt.User.Country)
                .Include(pt => pt.User.State)
                .Include(pt => pt.User.City)
                .Include(pt => pt.User.Database)
                .Include(pt => pt.User.UserAvatar)
                .SingleOrDefaultAsync(pt => pt.PatientFileId == Id);
        }

[HttpPut("{FileId}")]
public async Task<IActionResult> UpdatePatient([FromRoute] PatientFileIdResource fileIdModel, [FromBody] SavePatientsRegistryResource model)
{
    ApiSuccessResponder<PatientRegistryResource> response = new ApiSuccessResponder<PatientRegistryResource>();
    if (!ModelState.IsValid)
        return BadRequest(ModelState);
    Task<PatientRegistry> getPatientTask = repository.GetPatient(fileIdModel.FileId.Value);
    Task<RequestHeaderResource> getHeaderRequestTask = headerRequestService.GetUserHeaderData();
    await Task.WhenAll(getPatientTask, getHeaderRequestTask);
    PatientRegistry patient = await getPatientTask.ConfigureAwait(false);
    RequestHeaderResource header = await getHeaderRequestTask.ConfigureAwait(false);
    if (patient == null)
    {
        ModelState.AddModelError(string.Empty, "The patient does not exist in the database");
        return BadRequest(ModelState);
    }

    patient.DateNow = DateTime.Now;
    patient.AliasName = model.AliasName;
    await unitOfWork.CompleteAsync(header);
    return StatusCode(200, response);
}

现在,如果我用两个不同的用户访问同一个记录,并更改其中一个 AliasName 保存第二个访问记录的用户仍然可以保存新的更改,而不会出现并发异常。为什么这里的并发更新不会引发更新异常?

这是Fluent API配置,

 builder.Entity<PatientRegistry>()
        .Property(a => a.RowVersion).IsRowVersion()
        .IsConcurrencyToken()
        .ValueGeneratedOnAddOrUpdate();

我有更新日志 here

更新

根据文件 here ,我们可以通过在调用save之前操作其中一个值来测试并发冲突。

context.Database.ExecuteSqlCommand("UPDATE dbo.PatientsRegistry SET AliasName = 'Jane' WHERE PatientFileId = 2222");
await context.SaveChangesAsync();

这将引起一个例外。