Nullable Object Must Have a Value

nullable object must have a value

You should change the line this.MyDateTime = myNewDT.MyDateTime.Value; to just this.MyDateTime = myNewDT.MyDateTime;

The exception you were receiving was thrown in the .Value property of the Nullable DateTime, as it is required to return a DateTime (since that's what the contract for .Value states), but it can't do so because there's no DateTime to return, so it throws an exception.

In general, it is a bad idea to blindly call .Value on a nullable type, unless you have some prior knowledge that that variable MUST contain a value (i.e. through a .HasValue check).

EDIT

Here's the code for DateTimeExtended that does not throw an exception:

class DateTimeExtended
{
    public DateTime? MyDateTime;
    public int? otherdata;

    public DateTimeExtended() { }

    public DateTimeExtended(DateTimeExtended other)
    {
        this.MyDateTime = other.MyDateTime;
        this.otherdata = other.otherdata;
    }
}

I tested it like this:

DateTimeExtended dt1 = new DateTimeExtended();
DateTimeExtended dt2 = new DateTimeExtended(dt1);

Adding the .Value on other.MyDateTime causes an exception. Removing it gets rid of the exception. I think you're looking in the wrong place.

Nullable object must have a value?

You can always switch to

 fill.travel.GetValueOrDefault()

To provide the default (false), or the value of the boolean column from the database. Or you can specify the default with an overload. Either way, the nullable currently doesnt have a value, which is why you get that exception.

How to debug and fix 'Nullable object must have a value' within Entity Framework Core?

There can be two answers.

Firstly, this may be probably because your query is returning NULL and the model is not accepting null.

Second fix may be, if you are using anonymous types, then try typecasting the query result into nullable type.

e.g.

Id = (int?) op.Id,

how to find which property is returning NULL?

You can enable SQL Profiler and check the SQL query which is getting executed. Copy the query into SSMS and see which values are NULL.

This may be helpful for you to decide out if you really need nullable typecast OR you want to change the query itself.

There is an issue on GitHub on this page.

Update: 05-July-2021: How to find which property is returning NULL ?

You can use simple logging feature (introduced in EF core 5.0) by calling EnableDetailedErrors method.
Below code example shows how to configure Simple Logging for showing logs on Console and it also enables detailed errors.
If you do not want to show logs on console, then you can pass an action delegate in LogTo call, which accepts a string as parameter. This delegate can then write logs to any destination of your choice.

Refer documentation for more details.

protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    => optionsBuilder
        .LogTo(Console.WriteLine)
        .EnableDetailedErrors();

Linq Nullable object must have a value. errors in .NET 6 and EF Core

Try the following query:

var dataList = 
    from Class in _context.AllClass
    select new WinnerClassExtend
    {
        Class = Class,
        NumberOfWinnerinClass = _context.AllWinners.Where(w => w.ClassId == Class.ClassId).Count()
    };

var count = dataList.Count();

Or another one:

var grouped = 
    from Winner in _context.AllWinners
    group Winner by Class.ClassId into Group
    select new 
    {
        ClassId = Group.Key,
        NumberOfWinnerinClass = Group.Count()
    };

var dataList = 
    from Class in _context.AllClass
    join g in grouped on ClassId.ClassId equals g.ClassId
    select new WinnerClassExtend
    {
        Class = Class,
        NumberOfWinnerinClass = g.NumberOfWinnerinClass
    };

var count = dataList.Count();

In both cases compare execution plan.

DateTime Calculation Error InvalidOperationException: Nullable object must have a value

You need to make sure WaitlistReferralDate is not null like @Loong said.

public class TestModel
{
    public DateTime? date1 { get; set; }

    public int ListDay
    {
        get
        {
            DateTime valueNow = DateTime.Now;
            DateTime? valueRefer = date1;
            TimeSpan lday = valueNow - valueRefer;
            int day = (int)lday.TotalDays;
            return day;
        }
    }
}

public IActionResult Index()
{
    DateTime a = DateTime.Now.AddDays(-2);
    var model = new TestModel { date1 = a };
    return View(model);
}

@model TestModel

 <input asp-for="date1" class="form-control" />
 <input asp-for="ListDay" class="form-control" />

Nullable object must have a value while pass in stored procedure

You can change the call to check if the nullable DateTime filed has value and then use the Value property like

var cleardate = item.ClearDateC.HasValue ? (DateTime)item.ClearDateC : DateTime.Now;
MD.GetBankReco_GetBankRecoUpdate(item.CommentC, cleardate, item.Chqno, ChqDateC);

nullable object must have a value for datetime error

Your problem is happening on this line:

currentUser.Birthday.Value.ToString("dd-MM-yyyy");

If currentUser.Birthday is null, the .Value will throw the error. One suggestion could be:

ViewBag.Birthday = currentUser.Birthday?.Value.ToString("dd-MM-yyyy");

or

ViewBag.Birthday = currentUser.Birthday.HasValue ? currentUser.Birthday.Value.ToString("dd-MM-yyyy") : string.Empty;

Trying to allow nulls but... Nullable object must have a value

You are getting this error when trying to get value of nullable object, which do not have value. If Loan.ISBN property is not nullable then you should provide default value for that property

ISBN = student.ISBN.HasValue ? student.ISBN.Value : defaultValue
// or ISBN = student.ISBN ?? defaultValue
// or ISBN = student.ISBN.GetValueOrDefault()

If Loan.ISBN property is nullable, then simply assign student.ISBN without accessing Value of nullable type

ISBN = student.ISBN

---

Related Topics