993981-How to skip the unknown variables while using template marker

Document-Processing/Excel/Excel-Library/NET/faqs/how-to-fix-the-argument-out-of-range-exception-when-adding-more-then-one-marker-in-the-workbook.md

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+---
+title: Avoid Exceptions with Multiple XlsIO Template Markers | Syncfusion
+description: This page helps to prevent ArgumentOutOfRangeException when applying multiple template markers in Syncfusion .NET Excel library (XlsIO).
+platform: document-processing
+control: XlsIO
+documentation: UG
+---
+
+# How to avoid Exception when using multiple template markers in Excel?
+
+When processing multiple template markers in an Excel workbook with Syncfusion XlsIO, an ArgumentOutOfRangeException may occur if a marker variable is not found during an ApplyMarkers call. To prevent this, use [UnknownVariableAction.Skip](https://help.syncfusion.com/cr/document-processing/Syncfusion.XlsIO.ITemplateMarkersProcessor.html#Syncfusion_XlsIO_ITemplateMarkersProcessor_ApplyMarkers_Syncfusion_XlsIO_UnknownVariableAction_) for all ITemplateMarkersProcessor.ApplyMarkers calls except the final one. This ensures that any missing variables are gracefully ignored.
+
+The following code snippets illustrate how to use UnknownVariableAction.Skip when applying markers in C# (cross-platform and Windows-specific) and VB.NET.
+
+{% tabs %}  
+{% highlight c# tabtitle="C# [Cross-platform]" playgroundButtonLink="https://raw.githubusercontent.com/SyncfusionExamples/XlsIO-Examples/master/FAQ/Template%20Marker/.NET/TemplateMarker/TemplateMarker/Program.cs,180" %}
+using (ExcelEngine excelEngine = new ExcelEngine())
+{
+    IApplication application = excelEngine.Excel;
+    IWorkbook workbook = application.Workbooks.Open("../../../Data/InputTemplate.xlsx");
+
+    DataTable reports1 = new DataTable();
+    reports1.Columns.Add("SalesPerson");
+    reports1.Columns.Add("FromDate", typeof(DateTime));
+    reports1.Columns.Add("ToDate", typeof(DateTime));
+    reports1.Rows.Add("Andy Bernard", new DateTime(2014, 09, 08), new DateTime(2014, 09, 11));
+    reports1.Rows.Add("Jim Halpert", new DateTime(2014, 09, 11), new DateTime(2014, 09, 15));
+
+    //Create Template Marker Processor for Reports1
+    ITemplateMarkersProcessor marker1 = workbook.CreateTemplateMarkersProcessor();
+    //Add collection to marker variable
+    marker1.AddVariable("Reports1", reports1, VariableTypeAction.None);
+
+    //Process the markers in the template. Use UnknownVariableAction.Skip to ignore missing variables.
+    marker1.ApplyMarkers(UnknownVariableAction.Skip);
+
+    DataTable reports2 = new DataTable();
+    reports2.Columns.Add("SalesPerson");
+    reports2.Columns.Add("FromDate", typeof(DateTime));
+    reports2.Columns.Add("ToDate", typeof(DateTime));
+    reports2.Rows.Add("Karen Fillippelli", new DateTime(2014, 09, 15), new DateTime(2014, 09, 20));
+    reports2.Rows.Add("Phyllis Lapin", new DateTime(2014, 09, 21), new DateTime(2014, 09, 25));
+    reports2.Rows.Add("Stanley Hudson", new DateTime(2014, 09, 26), new DateTime(2014, 09, 30));
+
+    //Create Template Marker Processor for Reports2
+    ITemplateMarkersProcessor marker2 = workbook.CreateTemplateMarkersProcessor();
+    //Add collection to marker variable
+    marker2.AddVariable("Reports2", reports2, VariableTypeAction.None);
+
+    //This is the final ApplyMarkers call, so MissingVariableAction.Throw is acceptable (default behavior).
+    marker2.ApplyMarkers();
+
+    //Saving the workbook
+    workbook.Version = ExcelVersion.Xlsx;
+    workbook.SaveAs(Path.GetFullPath("../../../Output/TemplateMarker.xlsx"));
+}
+{% endhighlight %}
+
+{% highlight c# tabtitle="C# [Windows-specific]" %}
+using (ExcelEngine excelEngine = new ExcelEngine())
+{
+    IApplication application = excelEngine.Excel;
+    IWorkbook workbook = application.Workbooks.Open("../../Data/InputTemplate.xlsx");
+
+    DataTable reports1 = new DataTable();
+    reports1.Columns.Add("SalesPerson");
+    reports1.Columns.Add("FromDate", typeof(DateTime));
+    reports1.Columns.Add("ToDate", typeof(DateTime));
+    reports1.Rows.Add("Andy Bernard", new DateTime(2014, 09, 08), new DateTime(2014, 09, 11));
+    reports1.Rows.Add("Jim Halpert", new DateTime(2014, 09, 11), new DateTime(2014, 09, 15));
+
+    //Create Template Marker Processor for Reports1
+    ITemplateMarkersProcessor marker1 = workbook.CreateTemplateMarkersProcessor();
+    //Add collection to marker variable
+    marker1.AddVariable("Reports1", reports1, VariableTypeAction.None);
+
+    //Process the markers in the template. Use UnknownVariableAction.Skip to ignore missing variables.
+    marker1.ApplyMarkers(UnknownVariableAction.Skip);
+
+    DataTable reports2 = new DataTable();
+    reports2.Columns.Add("SalesPerson");
+    reports2.Columns.Add("FromDate", typeof(DateTime));
+    reports2.Columns.Add("ToDate", typeof(DateTime));
+    reports2.Rows.Add("Karen Fillippelli", new DateTime(2014, 09, 15), new DateTime(2014, 09, 20));
+    reports2.Rows.Add("Phyllis Lapin", new DateTime(2014, 09, 21), new DateTime(2014, 09, 25));
+    reports2.Rows.Add("Stanley Hudson", new DateTime(2014, 09, 26), new DateTime(2014, 09, 30));
+
+    //Create Template Marker Processor for Reports2
+    ITemplateMarkersProcessor marker2 = workbook.CreateTemplateMarkersProcessor();
+    //Add collection to marker variable
+    marker2.AddVariable("Reports2", reports2, VariableTypeAction.None);
+
+    //This is the final ApplyMarkers call, so MissingVariableAction.Throw is acceptable (default behavior).
+    marker2.ApplyMarkers();
+
+    //Saving the workbook
+    workbook.Version = ExcelVersion.Xlsx;
+    workbook.SaveAs(Path.GetFullPath("../../Output/TemplateMarker.xlsx"));
+}
+{% endhighlight %}
+
+{% highlight vb.net tabtitle="VB.NET [Windows-specific]" %}
+Using excelEngine As New ExcelEngine()
+    Dim application As IApplication = excelEngine.Excel
+    application.DefaultVersion = ExcelVersion.Xlsx
+    Dim workbook As IWorkbook = application.Workbooks.Open("../../Data/InputTemplate.xlsx")
+
+    Dim reports1 As New DataTable()
+    reports1.Columns.Add("SalesPerson")
+    reports1.Columns.Add("FromDate", GetType(DateTime))
+    reports1.Columns.Add("ToDate", GetType(DateTime))
+    reports1.Rows.Add("Andy Bernard", New DateTime(2014, 9, 8), New DateTime(2014, 9, 11))
+    reports1.Rows.Add("Jim Halpert", New DateTime(2014, 9, 11), New DateTime(2014, 9, 15))
+
+    ' Create Template Marker Processor for Reports1
+    Dim marker1 As ITemplateMarkersProcessor = workbook.CreateTemplateMarkersProcessor()
+    ' Add collection to marker variable
+    marker1.AddVariable("Reports1", reports1, VariableTypeAction.None)
+
+    ' Process the markers in the template. Use UnknownVariableAction.Skip to ignore missing variables.
+    marker1.ApplyMarkers(UnknownVariableAction.Skip)
+
+    Dim reports2 As New DataTable()
+    reports2.Columns.Add("SalesPerson")
+    reports2.Columns.Add("FromDate", GetType(DateTime))
+    reports2.Columns.Add("ToDate", GetType(DateTime))
+    reports2.Rows.Add("Karen Fillippelli", New DateTime(2014, 9, 15), New DateTime(2014, 9, 20))
+    reports2.Rows.Add("Phyllis Lapin", New DateTime(2014, 9, 21), New DateTime(2014, 9, 25))
+    reports2.Rows.Add("Stanley Hudson", New DateTime(2014, 9, 26), New DateTime(2014, 9, 30))
+
+    ' Create Template Marker Processor for Reports2
+    Dim marker2 As ITemplateMarkersProcessor = workbook.CreateTemplateMarkersProcessor()
+    ' Add collection to marker variable
+    marker2.AddVariable("Reports2", reports2, VariableTypeAction.None)
+
+    ' This is the final ApplyMarkers call, so MissingVariableAction.Throw is acceptable (default behavior).
+    marker2.ApplyMarkers()
+
+    ' Saving the workbook
+    workbook.Version = ExcelVersion.Xlsx
+    workbook.SaveAs("../../Output/TemplateMarker.xlsx")
+End Using
+{% endhighlight %}
+{% endtabs %}  
+
+A complete working example that shows how to apply number formatting to an entire column in Excel using C# is present on <a href="https://github.com/SyncfusionExamples/XlsIO-Examples/tree/master/FAQ/Template%20Marker/.NET/TemplateMarker">this GitHub page</a>.