Cannot insert the value NULL into column error - asp.net

Question

I am attempting to save user preferences into a table but am getting a null exception and I do not understand why. This is an MVC 4 application and this is my action result where I am getting the error.
public ActionResult Go(string path, string name)
{
RaterContext r = new RaterContext();
UserData u = new UserData();
var userid = u.GetCurrentUserData().UserId;
var info = r.RatersInfo.Where(w => w.RaterName.Equals(name)).FirstOrDefault();
var pref = r.RatersPreferences.Where(w => w.RaterId.Equals(info.RaterId) && w.UserId.Equals(userid)).FirstOrDefault();
if (pref != null && pref.Count > 0)
{
pref.Count++;
r.SaveChanges();
}
else
{
pref = new RaterPreferences();
pref.UserId = userid;
pref.RaterId = info.RaterId;
pref.Count = 1;
r.RatersPreferences.Add(pref);
r.SaveChanges();
}
return Redirect(path);
}
There is nothing saved in the preferences table yet so it is hitting the else block and throwing a null exception on r.SaveChanges();. The exception is
Cannot insert the value NULL into column 'UserId', table
'WebSiteNew.dbo.RaterPreferences'; column does not allow nulls. INSERT
fails.\r\nThe statement has been terminated.
The reason this doesn't make sense is because all three properties, including the UserId have data when I step through. These are the only fields in the table. UserId = 1, RaterId = 6 and Count is clearly set to 1. They are all set as non-nullable ints and the primary key is a combination of UserId and RaterId. My Model is as follows.
public class RaterContext : DbContext
{
public RaterContext()
: base("DefaultConnection")
{
}
public DbSet<RaterInfo> RatersInfo { get; set; }
public DbSet<RaterPreferences> RatersPreferences { get; set; }
}
[Table("RaterInfo")]
public class RaterInfo
{
[Key]
[DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
public int RaterId { get; set; }
public string RaterName { get; set; }
public string RaterLink { get; set; }
public string Section { get; set; }
public string Department { get; set; }
}
[Table("RaterPreferences")]
public class RaterPreferences
{
[Key]
[DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
public int UserId { get; set; }
public int RaterId { get; set; }
public int Count { get; set; }
}
Any help would be greatly appreciated as I am relatively new to MVC and ASP.NET. Let me know if you need more information. Thanks in advance!
I don't know if this helps but I tested to see what would happen on UPDATE by adding data manually so it would catch on the if block and that works. I'm only getting an error on INSERT.
Here is the create statement for the table in question.
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[RaterPreferences](
[UserId] [int] NOT NULL,
[RaterId] [int] NOT NULL,
[Count] [int] NOT NULL,
PRIMARY KEY CLUSTERED
(
[UserId] ASC,
[RaterId] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
ALTER TABLE [dbo].[RaterPreferences] WITH CHECK ADD CONSTRAINT [FK_RaterPreferences_RaterInfo] FOREIGN KEY([RaterId])
REFERENCES [dbo].[RaterInfo] ([RaterId])
GO
ALTER TABLE [dbo].[RaterPreferences] CHECK CONSTRAINT [FK_RaterPreferences_RaterInfo]
GO

Answer 1

I have copied your code into a brand new ASP.Net MVC project with the current version of Entity Framework and I am able to run your code with no problems. I escaped the UserData acquisition with code that looks like:
RaterContext r = new RaterContext();
//UserData u = new UserData();
var userid = 1; // u.GetCurrentUserData().UserId;
var info = r.RatersInfo.Where(w => w.RaterName.Equals(name)).FirstOrDefault();
and did not have a problem running the remainder of this code.
I think you may have some problems with your keys and database structure for the RaterPreferences table. I don't know your full data-model, but I don't understand how this fits in, and it is not keyed in your code the way that you describe.
Edit:
I've modified my database tables to reflect the design you've described. You have a difference between your EntityFramework code-first implementation and your database. It looks like your database existed first, and I would remove your EntityFramework classes and rebuild them with Database First techniques.