ReportParameter 中的空值处理

Question

因此，在此应用程序中，最终用户在一个表单上输入所需的 RMA 信息，然后可以选择将其加载到报告视图中并打印。因为这个数据库是多年前放在一起的，所以空值位于 [修复区域] 列中。我需要的是弄清楚如果检测到空值，如何将“区域”的参数值设置为“未知”。下面是当前使用的方法的代码。

public void GenerateServiceReport(string[] RMArray, string TempDataset, DataTable Results)
    {

        serviceReportViewer.LocalReport.ReportPath = "D:\\vsprojects\\projects\\emsdashboard\\emsdashboard\\RMAServiceReport.rdlc";

        ReportParameter dateReceived = new ReportParameter("DateParameter", RMArray[0]);
        serviceReportViewer.LocalReport.SetParameters(new ReportParameter[] { dateReceived });
        ReportParameter rmaNumber = new ReportParameter("RMAParameter", RMArray[1]);
        serviceReportViewer.LocalReport.SetParameters(new ReportParameter[] { rmaNumber });
        ReportParameter workOrder = new ReportParameter("WorkOrderParameter", RMArray[2]);
        serviceReportViewer.LocalReport.SetParameters(new ReportParameter[] { workOrder });
        ReportParameter qty = new ReportParameter("qtyParameter", RMArray[3]);
        serviceReportViewer.LocalReport.SetParameters(new ReportParameter[] { qty });
        ReportParameter company = new ReportParameter("CompanyParameter", RMArray[4]);
        serviceReportViewer.LocalReport.SetParameters(new ReportParameter[] { company });
        ReportParameter customer = new ReportParameter("CustomerParameter", RMArray[5]);
        serviceReportViewer.LocalReport.SetParameters(new ReportParameter[] { customer });
        ReportParameter ecn = new ReportParameter("ecnParameter", RMArray[6]);
        serviceReportViewer.LocalReport.SetParameters(new ReportParameter[] { ecn });
        ReportParameter warranty = new ReportParameter("WarrantyParameter", RMArray[7]);
        serviceReportViewer.LocalReport.SetParameters(new ReportParameter[] { warranty });
        ReportParameter action = new ReportParameter("ActionParameter", RMArray[8]);
        serviceReportViewer.LocalReport.SetParameters(new ReportParameter[] { action });
        ReportParameter part = new ReportParameter("PartParameter", RMArray[9]);
        serviceReportViewer.LocalReport.SetParameters(new ReportParameter[] { part });
        ReportParameter area = new ReportParameter("AreaParameter", RMArray[10]);
        serviceReportViewer.LocalReport.SetParameters(new ReportParameter[] { area });

        serviceReportViewer.LocalReport.DataSources.Clear();
        serviceReportViewer.LocalReport.DataSources.Add(new ReportDataSource(TempDataset, Results));
        serviceReportViewer.RefreshReport();
    }

private void RMAServiceReport_Load(object sender, EventArgs e) {

        this.serviceReportViewer.RefreshReport();
        this.serviceReportViewer.RefreshReport();
        this.serviceReportViewer.RefreshReport();
    }

Answer 1

更改像这样声明area 变量行

ReportParameter area = new ReportParameter("AreaParameter", RMArray[10] ?? "unknown");