Set format of cells produced by LoadFromCollection (epplus) using data annotation - data-annotations

Question

I am using eeplus to create an excel spreadsheet, like this
using (var pck = new ExcelPackage())
{
var ws = pck.Workbook.Worksheets.Add("Customers");
ws.Cells["A1"].LoadFromCollection(customers, PrintHeaders: true);
var ms = new System.IO.MemoryStream();
pck.SaveAs(ms);
ms.WriteTo(Response.OutputStream);
}
The customer class has properties like
[DisplayName("Customer creation date")]
public DateTime Created { get; set; }
DisplayName seems to get honored, so the topmost line will read Customer creation date but the cell contents show up as 43257,41667.
What I would really like to have is cells that has the format 2018-04-05.
Can I do that will data annotations? I tried both
[DisplayName("Customer creation date")]
[DisplayFormat(DataFormatString = "{0:yyyy-MM-dd}")]
public DateTime Created { get; set; }
and
[DisplayName("Customer creation date")]
[DataType(DataType.Date)]
public DateTime Created { get; set; }
but the cell contents remains the same.

Answer 1

No, EPPlus doesnot format your data according to data annotations.
It formats date as integers, so you should specify the column you wish to format as
ws.Column(colPosition+1).Style.Number.Format="yyyy-mm-dd";
You can find details here:
https://github.com/JanKallman/EPPlus/wiki/Formatting-and-styling
https://codereview.stackexchange.com/questions/139569/ensuring-specific-columns-in-an-excelworksheet-format-as-shortdate

Answer 2

EPPlus always changed column name while updating into excel based upon DisplayName Attribute else if there is no DisplayName Attribute is set, then it will Find "_" (underscore) character & replace it with " " (Space) Character in the column name, Due to which we cannot easily find PropertyInfo with help of column name to format the column as per our need.
Here is the simple & quickest solution to format column based upon indexing the PropertyInfo
PropertyInfo[] props = typeof(T).GetType().GetProperties(BindingFlags.Public | BindingFlags.Instance);
for (int i = 0; i < props.Length; i++)
{
Type t = props[i].PropertyType;
if (t == typeof(DateTime) || t == typeof(DateTime?))
ws.Column(i + 1).Style.Numberformat.Format = "dd-MMM-yyyy HH:mm:ss";
else if (t == typeof(TimeSpan) || t == typeof(TimeSpan?))
ws.Column(i + 1).Style.Numberformat.Format = "HH:mm:ss";
}
I have another solution if you need to format columns based upon column names.
void ApplyDateTimeFormatting<T>(ExcelWorksheet ws, IEnumerable<T> data)
{
if (data.Count() == 0)
return;
Type type = data.First().GetType();
for (int c = 1; c <= toColumns; c++)
{
string column = ws.Cells[1, c].Text;
var t = type.GetPropertyWithDisplayName<T>(column).PropertyType;
if (t == typeof(DateTime) || t == typeof(DateTime?))
ws.Column(c).Style.Numberformat.Format = "dd-MMM-yyyy HH:mm:ss";
else if (t == typeof(TimeSpan) || t == typeof(TimeSpan?))
ws.Column(c).Style.Numberformat.Format = "HH:mm:ss";
}
}
PropertyInfo GetPropertyFromDisplayName(Type type, string DisplayName)
{
MemberInfo[] members = type.GetProperties(BindingFlags.Public | BindingFlags.Instance);
foreach (var member in members)
{
DisplayNameAttribute displayNameAttribute = member
.GetCustomAttributes(typeof(DisplayNameAttribute), inherit: false)
.FirstOrDefault() as DisplayNameAttribute;
string text = ((displayNameAttribute == null) ? member.Name.Replace('_', ' ') :
displayNameAttribute.DisplayName);
if (text == DisplayName)
return type.GetProperty(member.Name);
}
return null;
}

Answer 3

I solved it as follows, so I just load the model and change as per my model if it is int or datetime
var li = typeof(Model).GetProperties().ToArray();
using (var package = new ExcelPackage(stream))
{
var workSheet = package.Workbook.Worksheets.Add("Sheet1");
var i = 0;
foreach (var c in li)
{
i++;
if(c.PropertyType.Name == typeof(DateTime).Name || c.PropertyType.Name == typeof(DateTime?).Name)
workSheet.Column(i).Style.Numberformat.Format = DateTimeFormatInfo.CurrentInfo.ShortDatePattern; ;
if (c.PropertyType.Name == typeof(int).Name || c.PropertyType.Name == typeof(int?).Name)
workSheet.Column(i).Style.Numberformat.Format = "0";
}
}