Accessing current users's download folder in dotnet core 2.0 and angular 2+

Question

I am a new developer and currently learning dotnet core angular technologies. I have a dotnet core project that allows me to download a SQL table as an excel file using EPPlus.Core library. When I test the code below, it works fine. I am able to get the excel file from my Downloads folder. However, when I publish it to the IIS, the code works fine but no files in the Downloads folder.

When I debug this, I realized that the frontend (in my case, it's angular) does not have access to my Downloads folder even though I explicitly declared in my controller. Here is my controller code that allows me to export as excel file.

[HttpGet]
[Route("ExportParticipants")]
public string ExportParticipants()
{
    string rootFolder =  System.Convert.ToString(
            Microsoft.Win32.Registry.GetValue(
            @"HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders"
                ,"{374DE290-123F-4565-9164-39C4925E467B}"
                ,String.Empty));
    var list = DateTime.Now.ToString("yyyy-MM-dd-HH-mmss");
    string fileName = @"Export_Participants_" + list + "_.xlsx";

    FileInfo file = new FileInfo(Path.Combine(rootFolder, fileName));

    using (ExcelPackage package = new ExcelPackage(file))
    {
        IList<Participant> participantList = context.Participants.ToList();
        ExcelWorksheet worksheet = package.Workbook.Worksheets.Add("Participants");
        int totalRows = participantList.Count();

        worksheet.Cells[1, 1].Value = "#";
        worksheet.Cells[1, 2].Value = "FirstName";
        worksheet.Cells[1, 3].Value = "Last Name";
        int i = 0;
        for (int row = 2; row <= totalRows + 1; row++)
        {
            worksheet.Cells[row, 1].Value = i+1;
            worksheet.Cells[row, 2].Value = participantList[i].FirstName;
            worksheet.Cells[row, 3].Value = participantList[i].LastName;
            i++;
        }

        package.Save();

    }

    return " Participant list has been exported successfully";
}

The code above works fine when I test it with postman. However, When I publish it, it doesn't work. I receive no error. But I found out that the issue is rootFolder. So I tried the following code:

string rootFolder = Environment.GetEnvironmentVariable("USERPROFILE") + @"\" + "Downloads";

And I even tried Ray Koopa's article in Code Project but I got the nothing in the downloads folder.

How can I place this exported excel file to the current user's Downloads folder? Please note that I use windows.

Or should I do this in the frontend? Should I look for a npm package and use it on the frontend? If so, which package you recommend it for me?

Thank you all for the help!

Answer 1

This will download the excel file inside the server's downloads folder. Instead of dealing with MemoryStream, I will use a frontend library. Since I have the list of participants in a JASON array form, DataTables library is a good one to go. It's not only to export excel, we can do pdf, print preview as well as a copy to the clipboard. I don't work for them. I have no affiliations with them. But I found it very useful in my case.