"Cannot insert the value NULL into column" with a non-null value

Question

This is the code I have:

Controller action method:

[HttpPost]
public ActionResult Create(Goal goal)
{
    if (ModelState.IsValid)
    {
        repository.SaveGoal(goal);
        return View("Index");
    }
    else
    {
        return View(goal);
    }
}

Model:

public class Goal
{
    [Required]
    public int GoalId { get; set; }

    [Required]
    public string Name { get; set; }

    [Required]
    [HiddenInput(DisplayValue = false)]
    public decimal Latitude { get; set; }

    [Required]
    [HiddenInput(DisplayValue = false)]
    public decimal Longitude { get; set; }

    [Required]
    public bool IsPrivate { get; set; }
}

Repository:

public class EFGoalRepository : IGoalRepository
{
    private EFDbContext context = new EFDbContext();

    public IQueryable<Goal> Goals
    {
        get { return context.Goals; }
    }

    public void SaveGoal(Goal goal)
    {
        context.Goals.Add(goal);
        context.SaveChanges(); // the line which causes the exception
    }
}

The problem: When I try to save a new Goal object with GoalId set to 0, I get the following error:

Cannot insert the value NULL into column 'GoalId', table 'TravelGoals.dbo.Goals'; column does not allow nulls. INSERT fails. The statement has been terminated.

I'm still new at ASP.NET MVC, but I believe this worked when I tried it a month ago with a different project.

All the values in my Goal object are valid (non-null, Name is of correct length). The GoalId property is set to 0, so it is not null either. I thought that Entity Framework would automatically assign a value to it.

What can I do to make this work?

Did you configure the ID to be a db generated column when you created the table in EF? — Liath
– Liath, Commented Jul 17, 2014 at 9:43
Apparently I didn't. I set the column to be identity in SQL Server, works as a charm now. Thank you! — user622505
– user622505, Commented Jul 17, 2014 at 9:47

user622505 · Accepted Answer · 2014-07-17 09:58:50Z

3

What I needed to do was setting the column as identity in SQL Server.

Probably the simplest way to do this (assuming you're using Visual Studio):

Open the SQL Server Object Explorer
Double-click the table you want to edit (or right-click and select View Designer)
Open the Properties window
Select the column in the Identity Column property as shown below

Properties window showing the Identity Column property

edited Jul 17, 2014 at 9:58

answered Jul 17, 2014 at 9:49

user622505

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1 Comment

Liath Over a year ago

If you're going to answer your own question I'd suggest adding a bit more detail about where/what etc so it's useful for future readers

Mohsen Esmailpour · Accepted Answer · 2014-07-17 10:02:05Z

1

Problem is GoalId is not identity.Put this attribut on GoalId

[Key]
public int GoalId { get; set; }

If your EF version is lower than 5 use this:

[Key]
[DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
public int GoalId { get; set; }

edited Jul 17, 2014 at 10:02

answered Jul 17, 2014 at 9:54

Mohsen Esmailpour

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