Question

Possible Duplicate:
What is a NullReferenceException in .NET?

I have a Model (ASP.NET MVC 4, C#) Called HoursOfOperation:

public class HoursOfOperation
{
    public List<DayTimes> Monday { get; set; }
    public List<DayTimes> Tuesday { get; set; }
    public List<DayTimes> Wednesday { get; set; }
    public List<DayTimes> Thursday { get; set; }
    public List<DayTimes> Friday { get; set; }
    public List<DayTimes> Saturday { get; set; }
    public List<DayTimes> Sunday { get; set; }
}

and a DayTimes

public class DayTimes
{
    public int Status { get; set; }
    public string From { get; set; }
    public string To { get; set; }
}

now I’m trying to add a new set to the Monday entity like below:

var _vm = new HoursOfOperation();

_vm.Monday.Add(new DayTimes{
      From = day.From.ToString(),
      To = day.To.ToString(),
      Status = (int)day.Status
});

as soon as the above statement is excecuted I’m getting a "Object reference not set to an instance of an object." Exception

Now I have checked and day.From.ToString() has a "08:00:00", day.To.ToString() has "09:30:00" and day.Status has a 1 at the time at which this statement throws the exception.

Any Ideas?

Answer 1

That’s because Monday is not instantiated.

You should do something like

_vm.Monday = new List<DayTimes>();

or alternatively, make all instantiations in HoursOfOperation‘s constructor like so:

public HoursOfOperation()
{
   Monday = new List<DayTimes>(),
   Tuesday = new List<DayTimes>(),
   Wednesday = new List<DayTimes>(),
   Thursday = new List<DayTimes>(),
   Friday = new List<DayTimes>(),
   Saturday = new List<DayTimes>(),
   Sunday = new List<DayTimes>()
};