并发异常

Question

我是唯一使用这个系统的用户，这段代码抛出一个并发异常，我所要做的就是更新状态并添加采用该任务的用户

OptimisticConcurrencyException:存储update、insert或delete语句影响到意外的行数(0)。实体可能已被修改或删除，因为实体是加载的。有关理解和处理乐观并发异常的信息，请参见http://go.microsoft.com/fwlink/?LinkId=472540。

     namespace GoldMine.View.Notification.Home.Process {
   using PageInstruction = GraphiteGTC.Core.View.Element.Model.PageInstruction;
    using Notification = GoldMine.Model.Notification;
    using User = GoldMine.Model.User;
    using NotificationApprovalStatus = GoldMine.Model.NotificationApprovalStatus;
    using ButtonTypeOption = GoldMine.Model.ButtonTypeOption;

    /// <summary>
    ///
    /// Class housing the logic for OnClickAdoptApproveTaskButtonProcess
    ///
    /// </summary>
    public class OnClickAdoptApproveTaskButtonProcess : GoldMineViewProcess {
        /// <summary>
        ///
        /// View process inputs
        ///
        /// </summary>
        public new OnClickAdoptApproveTaskButtonProcessInputs Inputs {
            get { return ( OnClickAdoptApproveTaskButtonProcessInputs )base.Inputs; }
            set { base.Inputs = value; }
        }

        /// <summary>
        ///
        /// View process outputs
        ///
        /// </summary>
        public new OnClickAdoptApproveTaskButtonProcessOutputs Outputs {
            get { return ( OnClickAdoptApproveTaskButtonProcessOutputs )base.Outputs; }
            set { base.Outputs = value; }
        }

        /// <summary>
        ///
        /// UI outputs
        ///
        /// </summary>
        public OnClickAdoptApproveTaskButtonProcessUiOutputs UiOutputs {
            get { return new OnClickAdoptApproveTaskButtonProcessUiOutputs( Outputs ); }
        }

        /// <summary>
        ///
        /// Default parameter-less constructor
        ///
        /// </summary>
        public OnClickAdoptApproveTaskButtonProcess() {
            Name = "GoldMine.View.Notification.Home.Process.OnClickAdoptApproveTaskButtonProcess";
            Inputs = new OnClickAdoptApproveTaskButtonProcessInputs();
            Outputs = new OnClickAdoptApproveTaskButtonProcessOutputs();
            base.Outputs = Outputs;
            base.Inputs = Inputs;
            DelayedPropertyAssignments = new List<DelayedPropertyAssignment>();
        }

        /// <summary>
        ///
        /// Entry point for event processing
        ///
        /// </summary>
        protected override GraphiteGTCProcess ExecuteProcess( GTCEventRegistration executingEventRegistration ) {
            return base.ExecuteProcess( Inputs.EventRegistration );
        }

        /// <summary>
        ///
        /// Entry point for Business Logic Processing
        ///
        /// </summary>
        protected override GraphiteGTCProcess ExecuteForwardProcessing() {
            try {
                Outputs = new OnClickAdoptApproveTaskButtonProcessOutputs();

                Outputs.SessionToken = UiStringConverter.CreateSessionToken( Inputs.CurrentUser );
                Debugging.DebugWorker.Current.BeginProcess();
                Debugging.DebugWorker.Current.SetVariableValue( "ButtonType", Inputs.ButtonType );
                Debugging.DebugWorker.Current.SetVariableValue( "CurrentNotification", Inputs.CurrentNotification );
                Debugging.DebugWorker.Current.SetVariableValue( "PageInstructions", Outputs.PageInstructions );
                Debugging.DebugWorker.Current.SetVariableValue( "CurrentUser", Inputs.CurrentUser );
                Debugging.DebugWorker.Current.BeginInstruction( "b60bbb93-3a06-4a57-ace3-6024f91c94a0", "092c84bf-423e-454b-8efa-00749bc691ef" );

                // ShapeComment:[Create List of Page Instructions][b60bbb93-3a06-4a57-ace3-6024f91c94a0][4bf395e3-e0a1-4304-b987-dcdae594a524]
                Debugging.DebugWorker.Current.BeginInstruction( "b60bbb93-3a06-4a57-ace3-6024f91c94a0", "4bf395e3-e0a1-4304-b987-dcdae594a524" );
                Outputs.PageInstructions = new List<PageInstruction>();
                Debugging.DebugWorker.Current.SetVariableValue( "PageInstructions", Outputs.PageInstructions );

                // ShapeComment:[Get Receiver][b60bbb93-3a06-4a57-ace3-6024f91c94a0][6b9c89cc-79c7-4957-8164-9a0c25da7652]
                Debugging.DebugWorker.Current.BeginInstruction( "b60bbb93-3a06-4a57-ace3-6024f91c94a0", "6b9c89cc-79c7-4957-8164-9a0c25da7652" );
                #region Execute FindReceiverFromNotification Process

                var notificationFindReceiverFromNotificationProcess = new Notification( true ).FindReceiverFromNotificationProcess;
                notificationFindReceiverFromNotificationProcess.Inputs.EventRegistration = Inputs.EventRegistration;
                notificationFindReceiverFromNotificationProcess.Inputs.CurreuntUser = Inputs.CurrentUser;
                notificationFindReceiverFromNotificationProcess.Inputs.Notification = Inputs.CurrentNotification;
                notificationFindReceiverFromNotificationProcess.OverriddenValidations = OverriddenValidations;
                try {
                    notificationFindReceiverFromNotificationProcess.StartProcessing();
                    Outputs.Validations.AddRange( notificationFindReceiverFromNotificationProcess.Outputs.Validations );
                }
                catch ( ValidationResultException validationResultException ) {
                    Outputs.Validations.AddRange( validationResultException.Validations );
                    if ( validationResultException.ContainsError() ) {
                        throw new ValidationResultException( string.Format( "Processing {0} resulted in an error", Name ), Outputs.Validations );
                    }
                }

                #endregion
                var NotificationFindReceiverFromNotificationResult = notificationFindReceiverFromNotificationProcess;
                Debugging.DebugWorker.Current.SetVariableValue( "NotificationFindReceiverFromNotificationResult", NotificationFindReceiverFromNotificationResult );

                // ShapeComment:[Assign Notification as Read][b60bbb93-3a06-4a57-ace3-6024f91c94a0][324e353c-cdd6-488e-8c9c-3420051a06f5]
                Debugging.DebugWorker.Current.BeginInstruction( "b60bbb93-3a06-4a57-ace3-6024f91c94a0", "324e353c-cdd6-488e-8c9c-3420051a06f5" );
                Inputs.CurrentNotification.AdoptedBy = Inputs.CurrentUser;
                Inputs.CurrentNotification.ApprovalStatus = NotificationApprovalStatus.Approved;

                // ShapeComment:[Save Notification][b60bbb93-3a06-4a57-ace3-6024f91c94a0][c407dd77-b074-4c26-ac9b-557d73fec312]
                Debugging.DebugWorker.Current.BeginInstruction( "b60bbb93-3a06-4a57-ace3-6024f91c94a0", "c407dd77-b074-4c26-ac9b-557d73fec312" );
                GoldMine.View.Notification.Home.Process.SaveNotificationProcess SaveNotificationProcessResult = null;
                try {
                    SaveNotificationProcessResult = ( GoldMine.View.Notification.Home.Process.SaveNotificationProcess ) EventProcess.ExecuteUnregisteredViewEvent( "GoldMine.View.Notification.Home.Process.SaveNotificationProcess", Inputs.CurrentUser, new NameValuePairInputCollection {
                        { "Notification", Inputs.CurrentNotification }
                    } );
                    Outputs.Validations.AddRange( SaveNotificationProcessResult.Outputs.Validations );
                }
                catch ( ValidationResultException validationResultException ) {
                    Outputs.Validations.AddRange( validationResultException.Validations );
                    if ( validationResultException.ContainsError() ) {
                        throw new ValidationResultException( string.Format( "Processing {0} resulted in an error", Name ), Outputs.Validations );
                    }
                }
                var HomeSaveNotificationResult = SaveNotificationProcessResult;
                Debugging.DebugWorker.Current.SetVariableValue( "HomeSaveNotificationResult", HomeSaveNotificationResult );
                Debugging.DebugWorker.Current.BeginInstruction( "b60bbb93-3a06-4a57-ace3-6024f91c94a0", "85d667f2-7ed7-4d91-9dff-1c25687fa197" );
                Debugging.DebugWorker.Current.EndProcess();
                Outputs.SessionToken = UiStringConverter.CreateSessionToken( Inputs.CurrentUser );
                return this;
            }
            *catch ( ConcurrencyException ) {
                throw;*
            }

Answer 1

请注意异常消息中的这一点：

影响了意外的行数(0)

这基本上意味着“我以为我要改变什么，但我最终什么也没改变”。

这可以在像UPDATE MyTable SET MyColumn = "hi" WHERE Id = 5这样的查询中实现，但是在Id of 5中没有记录。

如果在这两行之一上抛出异常：

Inputs.CurrentNotification.AdoptedBy = Inputs.CurrentUser;
Inputs.CurrentNotification.ApprovalStatus = NotificationApprovalStatus.Approved;

这意味着这些属性的setter方法正在写入数据库。属性定义如下所示：

User AdoptedBy {
    get {
         //something here
    }
    set {
        //this is writing to the database
    }
}

出于某种原因，它正在更新一些不存在的东西。但我们不能告诉你为什么或者如何解决它而不看到代码。

因此，它取决于对任何类型的Inputs.CurrentNotification的类定义。如果它是您的类之一，那么您可能只需要调试并逐步完成该代码。

实际上，在属性getter/getter中执行任何类型的I/O操作都不是一个好主意。