使用带有两个 DBContext 的 TransactionScope，得到错误

Question

我有一个使用TransactionScope 的函数。当我使用两个dbContext 时，它会崩溃。错误信息是：

System.Data.EntityException: Error underlying provider Open. ---> System.Transactions.TransactionException: The operation is not valid for the state of the transaction. in System.Transactions.TransactionState.EnlistPromotableSinglePhase (InternalTransaction tx, IPromotableSinglePhaseNotification promotableSinglePhaseNotification, Transaction AtomicTransaction, Guid promoterType) in System.Transactions.Transaction.EnlistPromotableSinglePhase (IPromotableSinglePhaseNotification promotableSinglePhaseNotification, Guid promoterType) in System.Transactions.Transaction.EnlistPromotableSinglePhase (IPromotableSinglePhaseNotification promotableSinglePhaseNotification) in System .Data.SqlClient.SqlInternalConnection.EnlistNonNull (Transaction tx) in System.Data.SqlClient.SqlInternalConnection.Enlist (Transaction tx)
in System.Data.ProviderBase.DbConnectionInternal.ActivateConnection (Transaction transaction) in System.Data.ProviderBase.DbConnectionPool.PrepareConnection (DbConnection owningObject, DbConnectionInternal obj, Transaction transaction) in System.Data.ProviderBase.DbConnectionPool.TryGetConnection (DbConnection owningObject, UInt32 waitForMultipleObjectsTimeout , allowCreate Boolean, Boolean onlyOneCheckConnection, DbConnectionOptions UserOptions, DbConnectionInternal & connection) in System.Data.ProviderBase.DbConnectionPool.TryGetConnection (DbConnection owningObject, TaskCompletionSource1 retry, DbConnectionOptions
  UserOptions, DbConnectionInternal & connection) in
  System.Data.ProviderBase.DbConnectionFactory.TryGetConnection (DbConnection
  owningConnection, TaskCompletionSource1 retry, DbConnectionOptions UserOptions, DbConnectionInternal oldConnection, DbConnectionInternal & connection) in System.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal (DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource1 retry, DbConnectionOptions UserOptions) in
  System.Data.SqlClient.SqlConnection.TryOpenInner (TaskCompletionSource1 retry) in System.Data.SqlClient.SqlConnection.TryOpen (TaskCompletionSource`1 retry) in System.Data.SqlClient.SqlConnection.Open () in System.Data.EntityClient.EntityConnection. OpenStoreConnectionIf (Boolean openCondition, DbConnection storeConnectionToOpen, DbConnection originalConnection, String ExceptionCode, attemptedOperation String, Boolean & closeStoreConnectionOnFailure)

代码

public void example(int c, IEnumerable<int> pi, string comm)
{
    using (var transactionScope = new TransactionScope(TransactionScopeOption.Required, new TransactionOptions { IsolationLevel = IsolationLevel.RepeatableRead }))
    {
        var idsList = pi.ToList();
        foreach (var playlist in Context.pl.Where(p => idsList.Contains(p.pid) && p.c== c&& p.stat== 1))
        {
            playlist.TimestampAuthorized = null;

            var pl = "sss";
            notif.generateNotifForUser((new Notification(1, 1, pl, 2, 2)));
        }
        Context.SaveChanges();
        transactionScope.Complete();
    }
}

问题出现在Context.SaveChanges()； 如果我评论notif.generateNotifForUser(); 行，它会起作用。进入那个函数，我也做context.saveChanges();

谢谢

Answer 1

// code before unchanged
foreach (var playlist in Context.pl.Where(p => idsList.Contains(p.pid) && p.c== c&& p.stat== 1).ToList()) // added ToList
// code after unchanged

问题与您尝试将开放连接用于两件事的事实有关。迭代 pl DbSet 结果以及您在 generateNotifForUser 中所做的任何事情，这可能是您从 DbContext 获取/执行其他操作的地方（根据您的更新，您正在调用 SaveChanges）。要解决此问题，请在您的 Lamda 语句末尾添加 ToList 以强制在迭代开始之前立即完全实现查询结果。然后连接将不再打开，允许您在代码的其他部分继续使用DbContext。这还假设您没有在方法链的下游犯下类似的错误。

Answer 2

编辑：

通知方法似乎导致了错误，因为它也调用了Context.SaveChanges

您只需拨打Context.SaveChanges一次

我会删除通知方法中的Context.SaveChanges，只在事务范围结束时调用它一次。