C#: EPPLUS: LoadFromCollection

Question

I have created a multidimensional list called Table, which is intended to be exported to an excel sheet. However, when I use the LoadFromCollection method, the resulting excel sheet only displays the following information.

Key   Value Item
File        System.Collections.Generic.List`1[System.String]    
Filter      System.Collections.Generic.List`1[System.String]    
Date        System.Collections.Generic.List`1[System.String]    

Actually, each list hast 168 items (making a 169x3 array, including the headers).

Here is the code.

private void button4_Click(object sender, EventArgs e)
{
        MultiDimDictList Table = new MultiDimDictList();
        Table.Add("File", new List<string>());
        Table.Add("Filter", new List<string>());
        Table.Add("Date", new List<string>());

    // IN THIS PART I POPULATE THE TABLE

        ExportToExcel(Table, @"c:\2.xlsx");
}

public void ExportToExcel(MultiDimDictList Matrix, string sourceFiles)
{
    FileInfo targetFile = new FileInfo(sourceFiles);

    using (var excelFile = new ExcelPackage(targetFile))
    {
        var worksheet = excelFile.Workbook.Worksheets.Add("Tables");
        var range = worksheet.Cells[2, 2];
        range.LoadFromCollection(Collection: Matrix, PrintHeaders: true);
        excelFile.Save();
    }
}

What I'm doing wrong?

Answer 1

I believe in your case it would be much better to use the LoadFromArrays method.

LoadFromCollection requires an IEnumerable of some type. Instead, you're giving it a type with three lists in it.

Using LoadFromArrays you could do this instead:

IEnumerable<object[]> GetAsEnumerable(MultiDimDictList table)
{
  yield return table.Columns.Select(i => (object)i.Name).ToArray();

  foreach (var row in table)
  {
    yield return table.Columns.Select(i => (object)row[i.Name]).ToArray();
  }
}

(of course, you have to modify this to suit your MultiDimDictList type; treat the sample as pseudo-code in where I assume how to load the column list and the row data)

And then just call

range.LoadFromArrays(GetAsEnumerable(Matrix));

Of course, you could also use LoadFromCollection , it's rather handy. But you'd have to use a different class than MultiDimDictList for the data. For example, the DataTable class should do just fine :)