当从事件作为循环的一部分进行调用时，ScriptBuffer会引发NullReferenceException-SSIS脚本组件

Question

我有一个SSIS程序包，它在循环中调用Data Flow Task，该循环迭代不同的端点地址（超出范围）。

Data Flow Task有一个源Script Component，它负责调用REST API并为每个结果创建一行。

有3个输出缓冲区；1.实际数据行2.错误行3.监控

用于遥测的监视缓冲区，并通过每次API发出请求时都会触发的事件（EventHander）进行填充。

在ForEach int Control Flow循环的第一次迭代中，所有内容均按预期运行，所有缓冲区产生正确的行。

但是，在下一次迭代中，事件中填充的监视缓冲区将抛出；

System.NullReferenceException: Object reference not set to an instance of an object.
   at Microsoft.SqlServer.Dts.Pipeline.ScriptComponentHost.HandleUserException(Exception e)
   at Microsoft.SqlServer.Dts.Pipeline.ScriptComponentHost.PrimeOutput(Int32 outputs, Int32[] outputIDs, PipelineBuffer[] buffers)
   at Microsoft.SqlServer.Dts.Pipeline.ManagedComponentHost.HostPrimeOutput(IDTSManagedComponentWrapper100 wrapper, Int32 outputs, Int32[] outputIDs, IDTSBuffer100[] buffers, IntPtr ppBufferWirePacket)

我不明白为什么MonitoringBuffer没有在后续的迭代中初始化。

调用MonitoringBuffer.AddRow();时发生异常。

这里是整个脚本组件的简化，以提高可读性：

[Microsoft.SqlServer.Dts.Pipeline.SSISScriptComponentEntryPointAttribute]
public class ScriptMain : UserComponent
{
    private string ClientCode { get { return Variables.ErplyClientCode; } }
    private string Username { get { return Variables.ErplyUsername; } }
    private string Password { get { return Variables.ErplyPassword; } }
    private bool IsTest { get { return Variables.IsTest; } }
    private int ErplyRecordsPerPage { get { return Variables.ErplyRecordsPerPage; } }
    private string ErplyDebugOutputPath { get { return Variables.ErplyDebugOutputPath; } }
    private DateTime ChangeSince { get { return Variables.ChangeSince; } }
    private int records { get; set; }
    private int errors { get; set; }
    private string rawFolder { get; set; }
    public override void PreExecute()
    {
        base.PreExecute();
    }

    public override void PostExecute()
    {
        base.PostExecute();
    }

    public override void CreateNewOutputRows()
    {
        ErplyAPI.OnPreRequestEvent += new EventHandler<EAPIEvent>(ErplyAPI_OnPreRequestEvent);

        var staff = ErplyAPI.getStaff(ClientCode, Username, Password, ChangeSince, ErplyRecordsPerPage, IsTest);
        foreach (var p in staff.List)
        {
            try
            {
                if (!p.IsError)
                {
                    EmployeeBuffer.AddRow();
                    EmployeeBuffer.employeeID = p.employeeID;
                }
                else
                {
                    ErrorBuffer.AddRow();
                    ErrorBuffer.employeeID = p.employeeID;
                    ErrorBuffer.Error = p.Error.Message.Trim() + "\n" + p.Error.StackTrace;
                    errors++;
                }
                records++;
            }
            catch (Exception ex)
            {
                this.ComponentMetaData.FireWarning(0, "Script", ex.Message + "\n" + ex.StackTrace, string.Empty, 0);
            }

        }

        EmployeeBuffer.SetEndOfRowset();
        ErrorBuffer.SetEndOfRowset();

    }

    private void ErplyAPI_OnPreRequestEvent(object sender, EAPIEvent e)
    {
        var request = string.Empty;
        var sessionKey = string.Empty;
        bool fireAgain = true;

        if (e == null)
        {
            ComponentMetaData.FireWarning(0, "SC_ERPLY_API", string.Format("EAPIEvent is NULL in ErplyAPI_OnPreRequestEvent. Amonit did not log the Erply request."), string.Empty, 0);
            return;
        }

        if (e.eAPI == null)
        {
            ComponentMetaData.FireWarning(0, "SC_ERPLY_API", string.Format("EAPIEvent.eAPI is NULL in ErplyAPI_OnPreRequestEvent. Amonit did not log the Erply request."), string.Empty, 0);
            return;
        }

        try
        {
            if (e.Parameters != null && e.Parameters.ContainsKey("request"))
                request = e.Parameters["request"].ToString();

            if (request != "verifyUser" && e.Parameters != null && e.Parameters.ContainsKey("sessionKey"))
                sessionKey = e.Parameters["sessionKey"].ToString();
        }
        catch (Exception ex)
        {
            ComponentMetaData.FireWarning(0, "SC_ERPLY_API", string.Format("Error occurred assigning variables from EAPIEvent parameters in ErplyAPI_OnPreRequestEvent. {0} {1}", ex.Message, ex.StackTrace), string.Empty, 0);
        }

        try
        {
            MonitoringBuffer.AddRow(); // Exception occurs here
            MonitoringBuffer.Request = ResizeString(request, 255);
            MonitoringBuffer.SessionKey = ResizeString(sessionKey, 128);
        }
        catch (Exception ex)
        {
            var message = string.Format("Error occurred outputting Erply request in ErplyAPI_OnPreRequestEvent. {0} {1}", ex.Message, ex.StackTrace);

            MonitoringBuffer.ErrorMessage = ResizeString(message, 8000);

            ComponentMetaData.FireWarning(0, "SC_ERPLY_API", message, string.Empty, 0);
        }
        finally
        {
            MonitoringBuffer.EndOfRowset();
        }
    }
}

Answer 1

从事件访问变量分配器时引发了异常。由于某些原因，GetValueWithContext(ScriptComponent.EvaluatorContext)在第二个通话中被丢弃。为什么发生这种情况超出了我。

解决方案很简单，将变量分配器中的变量分配给OnPreExecute函数中的局部属性或变量。

[不要在CreateNewOutputRows中调用变量分配器，因为它会导致变量锁定，也是一种好习惯。