迭代匿名类型列表的对象属性

Question

I am using EPPlus to create an "Export to Excel" helper. This will basically take an anonymous list and use that list to populate the spreadsheet.

I want to be able to iterate over the list object's properties and determine which is a datetime and format that column appropriately. The code I have below works, however is there a more succinct way to write this - specifically where I'm not depending on pulling an object from the list and operating on that object (ie I'm getting the property types from the list itself)?

    private static string[] columnIndex = "A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z".Split(',');
    private static ExcelWorksheet CreateAndFormatWorksheet<T>(OfficeOpenXml.ExcelPackage pck, List<T> dataSet)
    {
        ExcelWorksheet ws = pck.Workbook.Worksheets.Add("Monet_Export_" + DateTime.Now.ToString());
        ws.Cells["A1"].LoadFromCollection(dataSet, true);

        if (dataSet.Count > 0)
        {
            // Pull first list item to determine so we have something to iterate over below
            dynamic first = dataSet[0];

            // List count == upper row count for the spreadsheet
            string rowCount = dataSet.Count.ToString();

            int i = 0;
            foreach (PropertyInfo info in first.GetType().GetProperties())
            {
                if (info.PropertyType == typeof(DateTime))
                {
                    string column = columnIndex[i];
                    string indexer = column + "2:" + column + rowCount;
                    ws.Cells[indexer].Style.Numberformat.Format = "mm/dd/yyyy";
                }
                else if (info.PropertyType == typeof (int))
                {
                    string column = columnIndex[i];
                    string indexer = column + "2:" + column + rowCount;
                    ws.Cells[indexer].Style.Numberformat.Format = "@";                        
                }

                i++;
            }                
        }

        return ws;
    }

Answer 1

You can get the properties of the type T with typeof(T).GetProperties() . This works with anonymous types as well.

Then you don't need to pull out the first item to inspect its properties, and you don't have to check for dataSet.Count > 0 (if you want to allow an empty spreadsheet).