Question

我们使用数据优先方法，并使用Scaffol-Dbcontext对数据上下文进行反向工程。

数据库是MySql，我们使用Pomelo作为提供程序。

它对于283个数据库版本都可以正常工作，但是现在该命令因错误而崩溃：

命令超时在操作完成之前到期。

这是我使用的命令：

Scaffold-DbContext“服务器=本地主机；用户标识=用户；密码=通过；端口= 3306；数据库=数据库名称； sslmode =无；” “ Pomelo.EntityFrameworkCore.MySql” -d -o“ OutputFolder” -v -f-上下文 “ ContextName”

这是完整的堆栈跟踪：

MySql.Data.MySqlClient.MySqlException (0x80004005): The Command Timeout expired before the operation completed. ---> MySql.Data.MySqlClient.MySqlException (0x80004005): The Command Timeout expired before the operation completed.
   at MySqlConnector.Protocol.Serialization.BufferedByteReader.ReadBytesAsync(IByteHandler byteHandler, ArraySegment`1 buffer, Int32 totalBytesToRead, IOBehavior ioBehavior) in C:\projects\mysqlconnector\src\MySqlConnector\Protocol\Serialization\BufferedByteReader.cs:line 36
   at MySqlConnector.Protocol.Serialization.ProtocolUtility.ReadPacketAsync(BufferedByteReader bufferedByteReader, IByteHandler byteHandler, Func`1 getNextSequenceNumber, ProtocolErrorBehavior protocolErrorBehavior, IOBehavior ioBehavior) in C:\projects\mysqlconnector\src\MySqlConnector\Protocol\Serialization\ProtocolUtility.cs:line 406
   at MySqlConnector.Protocol.Serialization.ProtocolUtility.DoReadPayloadAsync(BufferedByteReader bufferedByteReader, IByteHandler byteHandler, Func`1 getNextSequenceNumber, ArraySegmentHolder`1 previousPayloads, ProtocolErrorBehavior protocolErrorBehavior, IOBehavior ioBehavior) in C:\projects\mysqlconnector\src\MySqlConnector\Protocol\Serialization\ProtocolUtility.cs:line 459
   at MySqlConnector.Protocol.Serialization.StandardPayloadHandler.ReadPayloadAsync(ArraySegmentHolder`1 cache, ProtocolErrorBehavior protocolErrorBehavior, IOBehavior ioBehavior) in C:\projects\mysqlconnector\src\MySqlConnector\Protocol\Serialization\StandardPayloadHandler.cs:line 37
   at MySqlConnector.Core.ServerSession.ReceiveReplyAsync(IOBehavior ioBehavior, CancellationToken cancellationToken) in C:\projects\mysqlconnector\src\MySqlConnector\Core\ServerSession.cs:line 645
--- End of stack trace from previous location where exception was thrown ---
   at MySqlConnector.Core.ServerSession.TryAsyncContinuation(Task`1 task) in C:\projects\mysqlconnector\src\MySqlConnector\Core\ServerSession.cs:line 1230
   at System.Threading.Tasks.ContinuationResultTaskFromResultTask`2.InnerInvoke()
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
--- End of stack trace from previous location where exception was thrown ---
   at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot)
--- End of stack trace from previous location where exception was thrown ---
   at MySqlConnector.Core.ResultSet.ReadResultSetHeaderAsync(IOBehavior ioBehavior) in C:\projects\mysqlconnector\src\MySqlConnector\Core\ResultSet.cs:line 42
   at MySql.Data.MySqlClient.MySqlDataReader.ActivateResultSet(ResultSet resultSet) in C:\projects\mysqlconnector\src\MySqlConnector\MySql.Data.MySqlClient\MySqlDataReader.cs:line 74
   at MySql.Data.MySqlClient.MySqlDataReader.ReadFirstResultSetAsync(IOBehavior ioBehavior) in C:\projects\mysqlconnector\src\MySqlConnector\MySql.Data.MySqlClient\MySqlDataReader.cs:line 299
   at MySql.Data.MySqlClient.MySqlDataReader.CreateAsync(MySqlCommand command, CommandBehavior behavior, ResultSetProtocol resultSetProtocol, IOBehavior ioBehavior) in C:\projects\mysqlconnector\src\MySqlConnector\MySql.Data.MySqlClient\MySqlDataReader.cs:line 284
   at MySqlConnector.Core.TextCommandExecutor.ExecuteReaderAsync(String commandText, MySqlParameterCollection parameterCollection, CommandBehavior behavior, IOBehavior ioBehavior, CancellationToken cancellationToken) in C:\projects\mysqlconnector\src\MySqlConnector\Core\TextCommandExecutor.cs:line 37
   at MySql.Data.MySqlClient.MySqlCommand.ExecuteDbDataReader(CommandBehavior behavior) in C:\projects\mysqlconnector\src\MySqlConnector\MySql.Data.MySqlClient\MySqlCommand.cs:line 252
   at Pomelo.EntityFrameworkCore.MySql.Scaffolding.Internal.MySqlDatabaseModelFactory.GetConstraints()
   at Pomelo.EntityFrameworkCore.MySql.Scaffolding.Internal.MySqlDatabaseModelFactory.Create(DbConnection connection, IEnumerable`1 tables, IEnumerable`1 schemas)
   at Pomelo.EntityFrameworkCore.MySql.Scaffolding.Internal.MySqlDatabaseModelFactory.Create(String connectionString, IEnumerable`1 tables, IEnumerable`1 schemas)
   at Microsoft.EntityFrameworkCore.Scaffolding.Internal.ReverseEngineerScaffolder.ScaffoldModel(String connectionString, IEnumerable`1 tables, IEnumerable`1 schemas, String namespace, String language, String contextDir, String contextName, ModelReverseEngineerOptions modelOptions, ModelCodeGenerationOptions codeOptions)
   at Microsoft.EntityFrameworkCore.Design.Internal.DatabaseOperations.ScaffoldContext(String provider, String connectionString, String outputDir, String outputContextDir, String dbContextClassName, IEnumerable`1 schemas, IEnumerable`1 tables, Boolean useDataAnnotations, Boolean overwriteFiles, Boolean useDatabaseNames)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.ScaffoldContextImpl(String provider, String connectionString, String outputDir, String outputDbContextDir, String dbContextClassName, IEnumerable`1 schemaFilters, IEnumerable`1 tableFilters, Boolean useDataAnnotations, Boolean overwriteFiles, Boolean useDatabaseNames)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.ScaffoldContext.<>c__DisplayClass0_1.<.ctor>b__0()
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.<>c__DisplayClass3_0`1.<Execute>b__0()
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action action)

相关的软件包版本：

Microsoft.AspNetCore.All 2.1.4
Pomelo.EntityFrameworkCore.MySql 2.1.2

请务必注意，这仅在我的计算机上发生（VS Professional 2017 v15.8.5）。其他同事可以运行相同的命令，并备份我的数据库，而不会出现任何错误。

您能指出我正确的方向吗？到目前为止，我已经测试（没有成功）：

更新所有软件包。
更新Visual Studio
删除nuget文件夹并还原软件包
尝试了多个数据库（有些工作，有些没有，但是不确定它们之间有什么区别
在连接字符串中添加了“ Connect timeout = 300”属性（相同的错误，但需要5分钟）

谢谢！

Answer 1

很抱歉，这个答案不能解决预期的问题，但是我需要在星期一工作，所以我走了co夫之路：

卸载与Visual Studio和MySQL有关的所有内容，然后再次重新安装，一切正常。

这也将Scaffold-DbContext运行所需的时间从3分钟减少到10秒。

仅作记录，我的上一个测试证明，仅导入具有5个以上FK约束的1个表，该过程将失败。删除任何FK可使该过程正常运行...

我的直觉告诉我某个地方的某个包装损坏导致了此问题。

Answer 2

下次，尝试添加

连接超时= 300（以秒为单位的时间）
默认命令超时= 300（以秒为单位的时间）

到您的连接字符串，如下所示：

dotnet ef dbcontext支架“ server = simycotest.ddns.net; userid = xxxxx; password = xxxxx; database = xxxxx; Connection Timeout = 300; default command timeout = 300”“ Pomelo.EntityFrameworkCore.MySql” -o。 DbModels -f

有关connection string in MySql

的更多信息

运行Scaffold-DbContext时发生超时错误

2 个答案: