将日期时间转换为日期字符串“dd/mm/yyyy”

Question

How can I convert DateTime to a string "dd/mm/yyyy"? The problem I'm having is that since the conversion is inside a linq expression I must use DateTime.Value.ToString("MM/dd/yyyy") . However, the date keeps coming back with the time-- 1/21/1999 12:00:00 AM . How can I remove the time part directly in this query?

_unitOfWork.PlacementFinancialViewRepository.GetEfs07Placements()
  .Where(x => x.FiscalYear == fiscalYear && x.ResponsibleSauId == responsibleDistrictId)
  .ToList()
  .Select(x => new Efs07PlacementModel
   {
     PlacementStartDate = x.PlacementStartDate == null 
       ? null 
       : x.PlacementStartDate.Value.ToString("MM/dd/yyyy"),
     PlacementEndDate = x.PlacementEndDate == null 
       ? null 
       : x.PlacementEndDate.Value.ToString("MM/dd/yyyy")
    })
  .ToList();

Answer 1

You may leave the List creation as is, with no conversion to the required format. So you may use you code as:

_unitOfWork.PlacementFinancialViewRepository.GetEfs07Placements().Where(x => x.FiscalYear == fiscalYear && x.ResponsibleSauId == responsibleDistrictId)
.ToList()
.Select(x => new Efs07PlacementModel
{
    PlacementStartDate = x.PlacementStartDate == null ? null : x.PlacementStartDate,
    PlacementEndDate = x.PlacementEndDate == null ? null : x.PlacementEndDate
}).ToList();

Then you can then convert the PlacementStartDate to your required format at the time yo uare displaying it on a View/UI.

Answer 2

A DateTime object is a count of milliseconds that have elapsed since midnight, January 1, 0001 AD. You are actually queering a number and automatically casting it into a DateTime (essentially). If your database has been saving the day but not the time, it will result in those milliseconds being set to 0. This is because you have just simply not added the milliseconds that represent the time of day.

You can, as others have stated, ignore the time or ensure that it is always set to midnight. Then in your displays set the format.

I would suggest doing this in your model object with System.ComponentModel.DataAnnotations .

[DisplayFormat(DataFormatString = "{0:dd/mm/yyyy}", ApplyFormatInEditMode = true)]

This way you can use @Html.DisplayFor(x => x.DateTimeObject) in your view and that sets your formatting.

Update:

In addition, you can add the attribute [DataType(DataType.Date)] in your object model. This will not change how the data is stored in the database by EF6, just how it is displayed by default. Some other ORM's may not behave this way so please read up on your ORM.

[DisplayFormat(DataFormatString = "{0:MM/dd/yyyy}", ApplyFormatInEditMode = true)]
[DataType(DataType.Date)]
public DateTime PlacementStartDate { get; set; }