无法将字符串转换为DateTime

Question

I have problem converting a string to DateTime,this is the error

I have used the solution showed in this link enter link description here and using DateTime.Parse,but I get this error all the time

this is my class Schedule:

 public partial class Schedule : BaseEntity
    {

        public string Day { get; set; }
        public string Note { get; set; }
        public DateTime Begin { get; set; }
        public DateTime End { get; set; }

     }

any help please and thanks Update:this is teh query

var Schedules = new List<Schedule>
{
    new Schedule
    { 
        Day="Lundi", Note="note", Begin=Convert.ToDateTime("2013-04-24 17:47:03"), 
        End=Convert.ToDateTime("2013-05-24 17:47:03"),
        ClassId = context.Classes.Where(c=>c.Libel=="Class 1").FirstOrDefault().Id, 
        SubjectLevelId = context.SubjectLevels.Where(cbv=>cbv.Coef==1).FirstOrDefault().Id, 
        ClassRoomId = context.ClassRooms.Where(c=>c.Libel=="ClassRoom1").FirstOrDefault().Id, 
        TeacherId = context.Teachers.Where(c=>c.FirstName=="mouna").FirstOrDefault().Id, 
        SchoolYearId=  context.SchoolYears.Where(f=>f.Begin==DateTime.Parse("15/09/2015")).FirstOrDefault().Id
    },
};
Schedules.ForEach(s =>
{
    s.ObjectState = Repository.Pattern.Infrastructure.ObjectState.Added;
    context.Schedules.Add(s);
    context.SaveChanges();
});

Answer 1

Change your code to something like this:

var beginDateTime = Convert.ToDateTime("2013-04-24 17:47:03");
var endDateTime = Convert.ToDateTime("2013-05-24 17:47:03");
var schoolYearBeginDate = DateTime.Parse("15/09/2015");
var Schedules = new List<Schedule>
{
    new Schedule
    { 
        Day="Lundi", 
        Note="note", 
        Begin = beginDateTime, 
        End=endDateTime,
        ClassId = context.Classes.Where(c=>c.Libel=="Class 1").FirstOrDefault().Id, 
        SubjectLevelId = context.SubjectLevels.Where(cbv=>cbv.Coef==1).FirstOrDefault().Id, 
        ClassRoomId = context.ClassRooms.Where(c=>c.Libel=="ClassRoom1").FirstOrDefault().Id, 
        TeacherId = context.Teachers.Where(c=>c.FirstName=="mouna").FirstOrDefault().Id, 
        SchoolYearId=  context.SchoolYears.Where(f=>f.Begin==schoolYearBeginDate).FirstOrDefault().Id
    },
};

Also, these will eventually throw a null reference exception:

context.Classes.Where(c=>c.Libel=="Class 1").FirstOrDefault().Id

Change them to:

context.Classes.Where(c=>c.Libel=="Class 1").Select(c => c.Id).FirstOrDefault()

If ClassId etc are not nullable, then you should do this:

context.Classes.Where(c=>c.Libel=="Class 1").First().Id

Answer 2

尝试在LINQ查询和DateTime.ParseExact方法中使用AsEnumerable

Begin = DateTime.ParseExact("2013-04-24 17:47:03", "yyyy-MM-dd HH:mm:ss", CultureInfo.InvariantCulture);

Answer 3

ParseExact will serve your purpose if you have specific date provided to this function, like shown below. And here is MSDN documentation about this method.

Begin = DateTime.ParseExact("2013-04-24 17:47:03", "yyyy-MM-dd HH:mm:ss", CultureInfo.InvariantCulture);

However ParseExact fails if you are providing date from some incoming text box or from other control, and date is absent there then it will throw a runtime error. To avoid that, best is to use TryParseExact . Read here from MSDN about TryParseExact.

Datetime dateTime;
bool isValid = DateTime.TryParseExact("2013-04-24 17:47:03", "yyyy-MM-dd HH:mm:ssy", CultureInfo.InvariantCulture, DateTimeStyles.None, out dateTime);

isValid will tell you if conversion was successful and dateTime will have your new converted date from string.