Passing parameters to subreport

[#1]

I have data loaded into dataset. I set up a crystal report with main report's datasource from ODBC database and subreport with dataset as datasource. I'm trying to pass parameters from main report to subreport. I linked main report's parameters to the corresponding fields in subreport and added filters in select expert.I get a NullReferenceException on parameterField.CurrentValues.Clear() with error"object reference not set to an instance of an object" and "parameterField was null".Here's my code:

        private ReportDocument mainReport;
        protected void Page_Init(object sender, EventArgs e)
        {
            //report loaded for first time
            if (!IsPostBack || (ReportDocument)Session["Report"] == null)
            {
                mainReport = new ReportDocument();
                mainReport.Load("C:\\Users\\userid\\Desktop\\application\\application.Web\\CrystalReport\\Reports\\CrystalReport1.rpt");

                //automatically log in to database without prompting the user 
                CrystalReportHelper.ConfigureCrystalReport(mainReport);

                DataSet ds1 = new DataSet("MovieDS");
                DataTable table = new DataTable("MovieDS");
                table.Columns.Add("TITLE", typeof(System.String));
                table.Columns.Add("YEAR", typeof(System.Int32));

                DataRow row1 = table.NewRow();
                row1["TITLE"] = "title_of_movie";
                row1["YEAR"] = 1992;

                table.Rows.Add(row1);
                ds1.Tables.Add(table);

                mainReport.Subreports[0].SetDataSource(ds1);

                //SET PARAMETERS
                SubreportSettingParameters_RD(mainReport, "subReport", "TITLE_PARAM", value);

                //remember loaded report
                Session.Add("Report", mainReport);
            }

            //connect crystal report viewer to display loaded report in session
            CrystalReportViewer1.ReportSource = (ReportDocument)Session["Report"];

            ////prevent prompting of parameters when report is opened
            CrystalReportViewer1.EnableParameterPrompt = false;
        }


        private void SubreportSettingParameters_RD(ReportDocument testReport, String subreportName, String parameterFieldName, String parameterValue)
        {
            ParameterDiscreteValue dv = new ParameterDiscreteValue();
            dv.Value = parameterValue;
            ParameterFields parameterFields = testReport.ParameterFields;
            ParameterField parameterField = parameterFields[parameterFieldName, subreportName];
            parameterField.CurrentValues.Clear();
            parameterField.CurrentValues.Add(dv);
        }

I'm using Crystal Report in Visual Studio Professional 2017. Thank you!

[former_member11696 · Accepted solution]

Hi Thuy,

There is no subreport parameter collection, it's all one collection off the main report collection. Code should work if you set the report name to nothing rather than the subreport name.

On the download page I have a parameter test app that may help you.

https://wiki.scn.sap.com/wiki/display/BOBJ/Crystal+Reports%2C+Developer+for+Visual+Studio+Downloads

Don

[Former Member · Accepted solution]

This works!

Now I'm running into another issue: optional parameters. EDIT: Solved this issue with mainReport.ParameterFields["PARAM_NAME"].CurrentValues.IsNoValue = true;

Thanks for your help, Don!

//original: SubreportSettingParameters_RD(mainReport, subReport, "param", "parama_value");
//change to this
SubreportSettingParameters_RD(mainReport, "", "PARAMETER_NAME", value);<br>