Issue with linq2sql with this specific stituation - linq-to-sql

Question

Software used:
Visual studio 2008 professional with services pack 1
Sql Server 2005 Standard Edition (9.00.4266.00)
Windows XP SP3
I have these 3 tables:
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
SET ANSI_PADDING ON
GO
CREATE TABLE [dbo].[Table_2](
[table2id] [int] IDENTITY(1,1) NOT NULL,
[table2filler] [varchar](max) NULL,
CONSTRAINT [PK_Table_2] PRIMARY KEY CLUSTERED
(
[table2id] 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
SET ANSI_PADDING OFF
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[Table_1](
[table1id] [int] IDENTITY(1,1) NOT NULL,
[table1guid] [uniqueidentifier] NOT NULL,
CONSTRAINT [PK_Table_1] PRIMARY KEY CLUSTERED
(
[table1id] 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
CREATE UNIQUE NONCLUSTERED INDEX [IX_Table_1] ON [dbo].[Table_1]
(
[table1guid] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
SET ANSI_PADDING ON
GO
CREATE TABLE [dbo].[Table_3](
[tableguid] [uniqueidentifier] NOT NULL,
[table2id] [int] NOT NULL,
[table3filler] [varchar](max) NULL,
CONSTRAINT [PK_Table_3] PRIMARY KEY CLUSTERED
(
[tableguid] ASC,
[table2id] 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
SET ANSI_PADDING OFF
GO
ALTER TABLE [dbo].[Table_3] WITH CHECK ADD CONSTRAINT [FK_Table_3_Table_1] FOREIGN KEY([tableguid])
REFERENCES [dbo].[Table_1] ([table1guid])
ON DELETE CASCADE
GO
ALTER TABLE [dbo].[Table_3] CHECK CONSTRAINT [FK_Table_3_Table_1]
GO
ALTER TABLE [dbo].[Table_3] WITH CHECK ADD CONSTRAINT [FK_Table_3_Table_2] FOREIGN KEY([table2id])
REFERENCES [dbo].[Table_2] ([table2id])
ON DELETE CASCADE
GO
ALTER TABLE [dbo].[Table_3] CHECK CONSTRAINT [FK_Table_3_Table_2]
GO
INSERT INTO [dbo].[Table_2]
([table2filler])
VALUES
('test')
print 'table2id:'
print scope_identity()
GO
declare #guid uniqueidentifier
set #guid=newid()
print 'table1guid:'
print #guid
INSERT INTO [dbo].[Table_1]
([table1guid])
VALUES
(#guid)
GO
now open a new web apps project, create a new dbml and drag&drop these 3 tables
now just put that code in a webpage codebehind
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Dim test As New Table_3
Dim db As New DataClasses1DataContext
test.table2id = 1
test.tableguid = New Guid("guid from table 1")
test.table3filler = "a"
db.Table_3s.InsertOnSubmit(test)
db.SubmitChanges()
End Sub
and run it
you will get an invalid cast error
only way so far for me to be able to run that code is to remove the link between the table inside the DBML
is there a way to do that insert without removing the link between the tables?

Answer 1

I actually created your database just as you specified and ran exactly this code it locally on my box. I get no such error when I substitute the a real GUID in this line:
test.tableguid = New Guid("guid from table 1")
Are you sure your GUIDs are in the right format? Are you sure your tables are created exactly like you specified? Double check it... My guess is that if you recreate this sample db from scratch, you won't see this problem.

Answer 2

I believe Linq2sql doesn't like it when you set a foreign key id directly. It prefers you to set the foreign object itself.
test.table_2 = db.Table_2.First(t2 => t2.table2id = 1);
test.tableguid = New Guid("guid from table 1")
test.table3filler = "a"

Answer 3

ok, it's in fact a bug with .net 3.5 and fixed with .net 4.0
but there is a hotfix, see detail here
everything work like it should after that hotfix is installed