Store update, insert, or delete statement affected an unexpected number of rows (0) EntityFramework [duplicate]

Question

I keep getting the following error when I try to save changes made to a context:

Store update, insert, or delete statement affected an unexpected number of rows (0). Entities may have been modified or deleted since entities were loaded. Refresh ObjectStateManager entries.

I have the following classes:

Person

public class Person : IPerson
{
    [Key]
    [DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
    public int Id { get; set; }
    public string FirstName { get; set; }

    public string LastName { get; set; }

    public string Name
    {
        get
        {
            return FirstName + " " + LastName;
        }
        set{}
    }

    public string Email { get; set; }
    public DateTime? LastModified { get; set; }
    public virtual ICollection<Result> Results { get; set; }
}

UserProfile

public class UserProfile : Person
{
    public UserProfile()
    {
        Faculty = new Faculty();
        Projects = new Collection<Project>();
        Results = new Collection<Result>();
    }
    public string UserName { get; set; }
    public string CNP { get; set; }
    public virtual Faculty Faculty { get; set; }
    public virtual ICollection<Project> Projects { get; set; }
}

Result

public abstract class Result:INamedEntity
{
    protected Result()
    {
        ResultType = new ResultType();
    }
    public int Id { get; set; }
    public string Name{get;set;}
    public virtual ResultType ResultType { get; set; }
    public virtual ICollection<Person> People { get; set; }
    public DateTime? LastModified { get; set; }
}

After I add a value to the context using:

_ctx.Users.Single(u => u.Id == userId).Results.Add(result);

I get the error when i call _ctx.SaveChanges()

Updated my function to:

public bool Save()
{

    try
    {
        _ctx.SaveChanges();
    }
    catch (OptimisticConcurrencyException)
    {
        ((IObjectContextAdapter)_ctx).ObjectContext.Refresh(RefreshMode.ClientWins,_ctx.Users);
        ((IObjectContextAdapter)_ctx).ObjectContext.Refresh(RefreshMode.ClientWins,_ctx.Results);
        _ctx.SaveChanges();
    }
    return true;
}

But the error isn't caught. Thank you

Answer 1

Add this to your edit.cshtml

@Html.HiddenFor(model => model.Id) 

I had this issue and found that the ID was coming across as 0 since it was not on the page.

I also have this on my ViewModel (I am using the view model approach)

[HiddenInput(DisplayValue = false)] [Key] public int Id { get; set; } 

Answer 2

Figured it out. The problem was that there's two of us working on this project, and my colleague created his own instance of DBContext he was updating one and i the other. So for who ever has this problem in the future make sure you don't have two different instances of your DBContext at the same time