tsilb tsilb - 10 months ago 57
C# Question

Linq to SQL: Why am I getting IDENTITY_INSERT errors?

I'm using Linq to SQL. I have a DataContext against which I am .SubmitChanges()'ing. There is an error inserting the identity field:

Cannot insert explicit value for identity column in table 'Rigs' when IDENTITY_INSERT is set to OFF.

The only identity field is "ID", which has a value of 0. It's defined in the DBML as:

[Column(Storage="_ID", AutoSync=AutoSync.OnInsert, DbType="Int NOT NULL IDENTITY", IsPrimaryKey=true, IsDbGenerated=true)]

There are a few foreign keys, and I've verified they have values that jive with the foreign tables' content.

Why would I be getting this error?

Edit: Here is the query:

exec sp_executesql N'INSERT INTO [dbo].[Rigs]([id], [Name], [RAM], [Usage], [MoreInfo], [datetime], [UID])
VALUES (@p0, @p1, @p2, @p3, @p4, @p5, @p6)
SELECT [t0].[id], [t0].[OSID], [t0].[Monitors]
FROM [dbo].[Rigs] AS [t0]
WHERE [t0].[id] = @p7',N'@p0 int,@p1 varchar(1),@p2 int,@p3 varchar(1),@p4 varchar(1),@p5 datetime,@p6 int,@p7
int',@p0=0,@p1='1',@p2=NULL,@p3='4',@p4='5',@p5=''2009-03-11 20:09:15:700'',@p6=1,@p7=0

Clearly it is passing a zero, despite having never been assigned a value.

Edit: Adding Code:

Rig rig = new Rig();
int RigID;
{ // Confirmed these always contain a nonzero value or blank
RigID = int.Parse(lbSystems.SelectedValue ?? hfRigID.Value);
if (RigID > 0) rig = mo.utils.RigUtils.GetByID(RigID);
catch { }

rig.Name = Server.HtmlEncode(txtName.Text);
rig.OSID = int.Parse(ddlOS.SelectedValue);
rig.Monitors = int.Parse(txtMonitors.Text);
rig.Usage = Server.HtmlEncode(txtUsage.Text);
rig.MoreInfo = Server.HtmlEncode(txtMoreInfo.Text);
foreach (ListItem li in lbYourCards.Items)
RigsToVideoCard r2vc = new RigsToVideoCard();
r2vc.VCID = int.Parse(li.Value);
rig.UID = c_UID > 0 ? c_UID : mo.utils.UserUtils.GetUserByToken(this.Master.LiveToken).ID;

if (!mo.utils.RigUtils.Save(rig))
throw new ApplicationException("There was an error saving your Rig. I have been notified.");
hfRigID.Value = rig.id.ToString();

public static User GetUserByToken(string token)
DataClassesDataContext dc = new DataClassesDataContext(ConfigurationManager.ConnectionStrings["MultimonOnlineConnectionString"].ConnectionString);
return (from u in dc.Users
where u.LiveToken == token
select u).FirstOrDefault();

Also, I notice that when I UPDATE an existing rig (insertonsubmit), it doesn't update. Profiler doesn't even show any queries being run.

Answer Source

Is your code setting the ID value explicitely to 0? (instead of leaving it untouched).

Update 1: As you posted on the updated version, linq2sql is clearly passing the value to the db. Here is one I haven't had any trouble with:

[Column(Storage="_CustomerID", AutoSync=AutoSync.Always, DbType="Int NOT NULL IDENTITY", IsDbGenerated=true)]
public int CustomerID

I just saw another one, and it has the same exact definition of the one you are using.

[Column(Storage="_TestID", AutoSync=AutoSync.OnInsert, DbType="Int NOT NULL IDENTITY", IsPrimaryKey=true, IsDbGenerated=true)]
public int TestID

Update 2: Regarding updates, you are not supposed to do InsertOnSubmit for that. Just update the values and call .SubmitChanges (should be throwing an exception). On the insert it is really weird, as the property attributes you posted seems to be correct, so the Insert method linq2sql generates should be correct as well. I would try, re-adding the table on the designer again and verifying all the properties are correct.

Note that the generated insert method should look like (with a matchingRig_Insert):

private void InsertRig(Rig obj)
	System.Nullable<int> p1 = obj.Id;

this.Rig_Insert(/* bunch of values */, ref p1); obj.Id = p1.GetValueOrDefault(); }