Using Linq to Sql, does not update, but does not throw exception

Question

Running .net 2008, asp.net, Linq to sql, sql server 2008 express

Foo f = db.Foo.First(x => x.ID == id);
f.IsValid = true;
db.SubmitChanges();

I have a very basic table, which has several fields, and no FK constraints. None of the data saves when I call .SubmitChanges(), but no error is thrown. Any ideas?

Not using any explicit transaction scope, fields are not autogenerated, and no triggers on the server.

score 4 · Accepted Answer · edited May 23 '17 at 12:32

4

Tyop aside, the first thing to try is setting db.Log = Console.Out; to see if any TSQL is issues (or better: run a SQL trace). If nothing is getting sent then maybe IsValid was already true - it won't re-save such changes unless it has to (unless you force it).

Less likely, you could perhaps have accidentally turning off object-tracking (db.ObjectTrackingEnabled).

Other common mistakes include:

not calling Complete() when using TransactionScope (if you are using TransactionScope)
with database files (rather than a separate server), checking in the original file (in the solution) rather than in the build output (typically /bin/debug or /bin/release).

I'm also assuming that IsValid is actually a db-mapped property (they don't have to be)

edited May 23 '17 at 12:32

Community

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answered Mar 22 '10 at 16:33

Marc Gravell

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Marking this as the solution, since it led me to the solution. – Russell Steen Mar 22 '10 at 16:38
@Marc this issue can also be caused by the table not having a PK defined. In this case LINQ to SQL will silently ignore changes. – Doctor Jones Apr 02 '13 at 14:18
And for those who using Entity Framework 6 `db.Database.Log = Console.Write` – PJ3 Jun 30 '16 at 15:15

score 2 · Answer 2 · answered Mar 22 '10 at 15:57

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You need to set IsValid on f and not on x.

Foo f = db.Foo.First(x => x.ID == id); 
f.IsValid = true; 
db.SubmitChanges();

And remember to call Complete on your TransactionScope if you are using one.

answered Mar 22 '10 at 15:57

Klaus Byskov Pedersen

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that was a typo. x.IsValid wouldn't compile, much less not throw an exception ;) Thanks for the catch – Russell Steen Mar 22 '10 at 16:30

score 2 · Answer 3 · answered Mar 22 '10 at 16:01

Is IsValid marked as an AutoGenerated field in the designer? If so, no changes that you make will be propagated back to the server. Also, is it possible that you have a DB trigger that may be running on update, instead of say on insert, that is setting it to a default value of 0 (false)?

score 1 · Answer 4 · answered Mar 22 '10 at 16:35

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Turns out that the primary key had been dropped from the DB since the last time I was working with this application. When I regenerated the .dbml recently it generated with no primary key. Adding that back in has fixed the problem.

answered Mar 22 '10 at 16:35

Russell Steen

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Using Linq to Sql, does not update, but does not throw exception

4 Answers4