ASP.NET核心EF - 上传文件时，遇到了一个错误

Question

我正在开发使用ASP.NET的核心系统，EF核心和我的数据库是MySQL和我使用MySQL Connector.NET的适配器。

我在我的系统中一个地方，用户可以选择一个文件并上传。我的问题是，当我尝试上传一个文件，该文件是1000多KB，我收到以下错误：

一个已建立的连接被软件在主机中止

此文件的数据库字段是LONGBLOB类型和模式的类型是byte[]。该错误是正确这就是为什么它是难以调试，并查明原因的dbcontext.SaveChanges()方法内抛出。

我会后下面的完整堆栈跟踪：

   at MySqlConnector.Protocol.Serialization.SocketByteHandler.WriteBytesAsync(ArraySegment`1 data, IOBehavior ioBehavior) in C:\projects\mysqlconnector\src\MySqlConnector\Protocol\Serialization\SocketByteHandler.cs:line 90
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at MySqlConnector.Utilities.ValueTaskExtensions.<ContinueWith>d__0`2.MoveNext() in C:\projects\mysqlconnector\src\MySqlConnector\Utilities\ValueTaskExtensions.cs:line 8
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at MySqlConnector.Core.ServerSession.TryAsyncContinuation(Task`1 task) in C:\projects\mysqlconnector\src\MySqlConnector\Core\ServerSession.cs:line 1225
   at System.Threading.Tasks.ContinuationResultTaskFromResultTask`2.InnerInvoke()
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot)
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at MySqlConnector.Core.TextCommandExecutor.<ExecuteReaderAsync>d__1.MoveNext() in C:\projects\mysqlconnector\src\MySqlConnector\Core\TextCommandExecutor.cs:line 36
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at MySql.Data.MySqlClient.MySqlCommand.<ExecuteNonQueryAsync>d__60.MoveNext() in C:\projects\mysqlconnector\src\MySqlConnector\MySql.Data.MySqlClient\MySqlCommand.cs:line 261
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at MySql.Data.MySqlClient.MySqlCommand.ExecuteNonQuery() in C:\projects\mysqlconnector\src\MySqlConnector\MySql.Data.MySqlClient\MySqlCommand.cs:line 62
   at MySql.Data.MySqlClient.MySqlTransaction.Dispose(Boolean disposing) in C:\projects\mysqlconnector\src\MySqlConnector\MySql.Data.MySqlClient\MySqlTransaction.cs:line 81
   at Microsoft.EntityFrameworkCore.Storage.RelationalTransaction.Dispose()
   at Microsoft.EntityFrameworkCore.Update.Internal.BatchExecutor.Execute(DbContext _, ValueTuple`2 parameters)
   at Pomelo.EntityFrameworkCore.MySql.Storage.Internal.MySqlExecutionStrategy.Execute[TState,TResult](TState state, Func`3 operation, Func`3 verifySucceeded)
   at Microsoft.EntityFrameworkCore.Update.Internal.BatchExecutor.Execute(IEnumerable`1 commandBatches, IRelationalConnection connection)
   at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.SaveChanges(IReadOnlyList`1 entriesToSave)
   at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.SaveChanges(Boolean acceptAllChangesOnSuccess)
   at Microsoft.EntityFrameworkCore.DbContext.SaveChanges(Boolean acceptAllChangesOnSuccess)
   at Zoneberry.Repository.ZONContext.SaveChanges() in path\ZONContext.cs:line 157
   at path.Commit() in project\UnitOfWork.cs:line 419
   at project.Controller.UploadFileFor(List`1 files, Int32 leadId, Int32 totalCount) in project\Controllers\LeadController.cs:line 220
   at lambda_method(Closure , Object , Object[] )
   at Microsoft.Extensions.Internal.ObjectMethodExecutor.Execute(Object target, Object[] parameters)
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.<InvokeActionMethodAsync>d__12.MoveNext()

当我上传它的小于1MB的文件系统工作正常。

Answer 1

也许你有一个MySql侧的限制。尝试MySql服务器上执行以下命令：

SHOW VARIABLES LIKE 'max_allowed_packet';

如果结果是近1 million字节，那么你就需要增加运行以下命令值（例如近2 MB）：

SET GLOBAL max_allowed_packet=2000000;

但这种设置将服务器重新启动后复位。要永久更改设置，你需要改变它的下my.ini部分~/.my.cnf或[mysqld]：

max_allowed_packet=2M