/// <summary>
/// Reads a field, as a string.
/// </summary>
/// <param name="key">The column</param>
/// <returns>The value</returns>
/// <exception cref="InvalidCastException"></exception>
public string GetString(string key)
{
Cell cell = GetCell(key);
if (cell == null)
{
return(null);
}
string result = ExcelCellFormatter.CellToString(cell, _document);
result = result?.Trim( );
return(result);
}
