实体框架 - “由于在会话中运行的其他线程”不允许新事务“ [英] Entity Framework - "New transaction is not allowed because there are other threads running in the session"

问题描述

System.Data.SqlClient.SqlException：新事务是不允许，因为会话中还有其他线程。

我已经看到了这个问题的各种答案，但我似乎不能得到他们中的任何一个工作，基本上我正在保存我的存储库内的一个事务中的大量项目，我必须循环通过几个项目删除它们并写一个审计记录。

我已经看到的所有其他答案（例如 Mark Staffords答案）建议声明一个明确的事务（我有），或者在完成循环后只调用保存更改（这不是一个选项，因为审计目前工作的方式 - 需要审计ID写审核详细记录）。 p>

每当在delete方法中调用SaveChanges时，会抛出错误，请参见下文 -

 code> public virtual void Save（DoseReturn oldDoseReturn）
 {
 //保存开始时获取日期时间
 DateTime saveStartTime = DateTime.Now; 
字典< string，object> oldValues = new Dictionary< string，object>（）; 
字典< string，object> newValues = new Dictionary< string，object>（）; 
 
 //获取对象上下文并打开一个新事务
 ObjectContext objectContext =（（IObjectContextAdapter）context）.ObjectContext; 
 objectContext.Connection.Open（）; 
 DbTransaction transaction = objectContext.Connection.BeginTransaction（）; 
 
 //使用事务处理所有更新
使用（transaction）
 {
 if（oldDoseReturn！= null）
 {
 IDoseReturnStatusRepository statusRepository = new DoseReturnStatusRepository（）; 
 var list = statusRepository.AsQueryable（）。其中​​（x => x.DoseReturnID == oldDoseReturn.DoseReturnID）; 
 
 foreach（列表中的var项）
 {
 statusRepository.Delete（item，objectRetrievedDateTime，objectContext，saveStartTime，out oldValues，out newValues）; 
} 
 
 context.SaveChanges（）; 
 
 //获取相关的存储库
 IDoseReturnsRepository repository = new DoseReturnsRepository（）; 
 
 //审计和删除对象
 repository.Delete（oldDoseReturn，objectRetrievedDateTime，objectContext，saveStartTime，out oldValues，out newValues）; 
 
 context.SaveChanges（）; 
} 
} 
 
 try 
 {
 //进行最后的保存，然后提交事务
 context.SaveChanges（）; 
 transaction.Commit（）; 
} 
 catch（Exception ex）
 {
 //发生错误，回滚事务并关闭连接，然后出现错误
 transaction.Rollback（ ）; 
 objectContext.Connection.Close（）; 
 throw ex; 
} 
 //关闭连接
 objectContext.Connection.Close（）; 
 
 
 public virtual void Delete（T entity，DateTime？objectRetrievedDateTime，ObjectContext objectContext，DateTime saveStartTime，out Dictionary< string，object> oldValues，out Dictionary< string，object> newValues）
 {
 oldValues = new Dictionary< string，object>（）; 
 newValues = new Dictionary< string，object>（）; 
 
 if（entity == null）
 {
 throw new ArgumentException（无法更新空实体）; 
} 
 
 string entityName = entity.GetType（）。Name; 
 
 if（！objectRetrievedDateTime.HasValue ||！this.AuditsAfterRetieval（objectRetrievedDateTime，entityName，entity，saveStartTime））
 {
 this.DeletedEntityAudit（entity，out oldValues，out newValues ）; 
 
 context.Entry（entity）.State = System.Data.EntityState.Deleted; 
 this.context.Set&T;（）。Remove（entity）; 
 this.Audit（entity，entityName，Delete，oldValues，newValues，true）; 
 this.context.SaveChanges（）; 
} 
 else 
 {
 throw new Exception（Object is not be as as it has been modified in another thread）; 
} 
} 
  

解决方案

可能是因为您在尝试保存更改时枚举结果。

尝试更改此行：

  var list = statusRepository.AsQueryable （）
 .Where（x => x.DoseReturnID == oldDoseReturn.DoseReturnID）; 
  

to：

 code> var list = statusRepository.AsQueryable（）
 .Where（x => x.DoseReturnID == oldDoseReturn.DoseReturnID）
 .ToList（）; 
  

作为辅助调用 .SaveChanges（）


I am getting the following error trying to save changes in entity framework -

System.Data.SqlClient.SqlException: New transaction is not allowed because there are other threads running in the session.

I have seen various answers to this problem, but I cannot seem to get any of them to work, basically I am saving a large number of items in a transaction inside my repository, I have to loop through several items to delete them and write an audit record.

All other answers I have seen for this (E.g. Mark Staffords Answer) suggest declaring an explicit transaction (which I have) or by only calling save changes after completing the loop (this is not an option due to the way auditing currently works - the audit ID is required to write the audit details records).

The error is thrown whenever 'SaveChanges' is called inside the delete method, see below -

public virtual void Save(DoseReturn oldDoseReturn)
{
    // Get the datetime when the save started
    DateTime saveStartTime = DateTime.Now;
    Dictionary<string, object> oldValues = new Dictionary<string, object>();
    Dictionary<string, object> newValues = new Dictionary<string, object>();

    // Get the object context and open a new transaction
    ObjectContext objectContext = ((IObjectContextAdapter)context).ObjectContext;
    objectContext.Connection.Open();
    DbTransaction transaction = objectContext.Connection.BeginTransaction();

    // Use the transaction for all updates
    using (transaction)
    {
        if (oldDoseReturn != null)
        {
              IDoseReturnStatusRepository statusRepository = new DoseReturnStatusRepository();
              var list = statusRepository.AsQueryable().Where(x => x.DoseReturnID == oldDoseReturn.DoseReturnID);

              foreach (var item in list)
              {
                  statusRepository.Delete(item, objectRetrievedDateTime, objectContext, saveStartTime, out oldValues, out newValues);
              }

              context.SaveChanges();

              // Get the relevant repository
              IDoseReturnsRepository repository = new DoseReturnsRepository();

              // audit and delete the object
              repository.Delete(oldDoseReturn, objectRetrievedDateTime, objectContext, saveStartTime, out oldValues, out newValues);

              context.SaveChanges();
         }
    }

    try
    {
         // Conduct a final save, then commit the transaction
         context.SaveChanges();
         transaction.Commit();
    }
    catch (Exception ex)
    {
         // An error has occurred, rollback the transaction and close the connection, then present the error
         transaction.Rollback();
         objectContext.Connection.Close();
         throw ex;
    }
    // Close the connection
    objectContext.Connection.Close();
}

public virtual void Delete(T entity, DateTime? objectRetrievedDateTime, ObjectContext objectContext, DateTime saveStartTime, out Dictionary<string, object> oldValues, out Dictionary<string, object> newValues)
    {
        oldValues = new Dictionary<string, object>();
        newValues = new Dictionary<string, object>();

        if (entity == null)
        {
            throw new ArgumentException("Cannot update a null entity.");
        }

        string entityName = entity.GetType().Name;

        if (!objectRetrievedDateTime.HasValue || !this.AuditsAfterRetieval(objectRetrievedDateTime, entityName, entity, saveStartTime))
        {
            this.DeletedEntityAudit(entity, out oldValues, out newValues);

            context.Entry(entity).State = System.Data.EntityState.Deleted;
            this.context.Set<T>().Remove(entity);
            this.Audit(entity, entityName, "Delete", oldValues, newValues, true);
            this.context.SaveChanges();
        }
        else
        {
            throw new Exception("Object cannot be saved as it has been amended in another thread");
        }
    }

解决方案

This might be because you are enumerating results when trying to save changes.

Try changing this line:

var list = statusRepository.AsQueryable()
               .Where(x => x.DoseReturnID == oldDoseReturn.DoseReturnID);

to:

var list = statusRepository.AsQueryable()
               .Where(x => x.DoseReturnID == oldDoseReturn.DoseReturnID)
               .ToList();

As a side note invoking .SaveChanges() inside a loop is usually not a good idea as it is in general an expensive operation (talks to the database).

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