经常保存实体框架

Question

使用实体框架4.3.1数据库首先,经常提交/保存对象更改到数据库的好方法是什么？在下面,我想在quickbooks电话之后立即保存发票,而不是等待发布所有发票的风险.但是,我不能每次在循环中调用SaveChanges,它会抛出异常.

在每个对象上使用.Save()方法会很方便,也许有一个很好的方法可以做到这一点？

var unpostedInvoices = entities.GetUnpostedInvoices();
foreach (Invoice invoice in unpostedInvoices)
{
    // this takes a long time
    var invoiceDto = quickbooks.PostInvoice(invoice);

    invoice.Posted = true;
    invoice.TransactionId = invoiceDto.TransactionId;

    // I'd like to save here rather than after the foreach loop, but this will fail
    //entities.SaveChanges();
}

// this works, but I don't want to risk waiting this long to save
entities.SaveChanges();

这是在循环中调用SaveChanges()时抛出的异常.

New transaction is not allowed because there are other threads running in the session.

at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)
at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)
at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj, Boolean callerHasConnectionLock, Boolean asyncClose)
at System.Data.SqlClient.TdsParser.TryRun(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj, Boolean& dataReady)
at System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj)
at System.Data.SqlClient.TdsParser.TdsExecuteTransactionManagerRequest(Byte[] buffer, TransactionManagerRequestType request, String transactionName, TransactionManagerIsolationLevel isoLevel, Int32 timeout, SqlInternalTransaction transaction, TdsParserStateObject stateObj, Boolean isDelegateControlRequest)
at System.Data.SqlClient.SqlInternalConnectionTds.ExecuteTransactionYukon(TransactionRequest transactionRequest, String transactionName, IsolationLevel iso, SqlInternalTransaction internalTransaction, Boolean isDelegateControlRequest)
at System.Data.SqlClient.SqlInternalConnectionTds.ExecuteTransaction(TransactionRequest transactionRequest, String name, IsolationLevel iso, SqlInternalTransaction internalTransaction, Boolean isDelegateControlRequest)
at System.Data.SqlClient.SqlInternalConnection.BeginSqlTransaction(IsolationLevel iso, String transactionName)
at System.Data.SqlClient.SqlInternalConnection.BeginTransaction(IsolationLevel iso)
at System.Data.SqlClient.SqlConnection.BeginDbTransaction(IsolationLevel isolationLevel)
at System.Data.Common.DbConnection.BeginTransaction(IsolationLevel isolationLevel)
at System.Data.EntityClient.EntityConnection.BeginDbTransaction(IsolationLevel isolationLevel)

Answer 1

这个问题可能有所帮助:https://stackoverflow.com/questions/2113498

您仍在读取结果集时无法启动新事务,并且SaveChanges如果尚未存在事务,则创建事务.

一种解决方案是首先完成读取,然后迭代内存中的结果集.

如果您更改此行:

var unpostedInvoices = entities.GetUnpostedInvoices().ToList();

你能把它放SaveChanges回到循环中吗？