Question

I’d like to create a dynamic list based on a list of data (unknown count) in a different worksheet from where the data resides using the .NET EPPlus library when creating an Excel file (xlsx). How can I accomplish this?

Manual workflow in Excel 2007:
1.) click on sheet2 (dropdowns worksheet)
2.) add some data from cell A2:A4
3.) click on sheet1 (data worksheet) > highlight cells in some column > Data (menu) > Data Validation > Data Validation > Allow: List, Source: ='sheet2'!$A$2:$A$4 > click 'OK'

Answer 1

Hopefully this will help. For more detailed examples on data validations download the EPPlus sample app from codeplex and check out Sample 11.

// add a validation and set values
        var validation = sheet.DataValidations.AddListValidation("A1");
        // Alternatively:
        // var validation = sheet.Cells["A1"].DataValidation.AddListDataValidation();
        validation.ShowErrorMessage = true;
        validation.ErrorStyle = ExcelDataValidationWarningStyle.warning;
        validation.ErrorTitle = "An invalid value was entered";
        validation.Error = "Select a value from the list";
        validation.Formula.ExcelFormula = "B2:B4";