I had a weird Serialization problem with Linq to SQL the other day and since I didn’t Google the fix I figured I’d publish it here.

I had a table which refers to itself, something like this:

CREATE TABLE [dbo].[node](
[id] [int] IDENTITY(1,1) NOT NULL,
[title] [nvarchar](50) NOT NULL,
[parentId] [int] NULL,
CONSTRAINT [PK_node] PRIMARY KEY CLUSTERED
(
[id] ASC
)
ALTER TABLE [dbo].[node]  WITH CHECK ADD  CONSTRAINT [FK_node_node] FOREIGN KEY([parentId])
REFERENCES [dbo].[node] ([id])

I have a stored function to retrieve all the nodes, including their descendants from the DB, mine’s based on the function included here [LINK]

Once I got the rows, I was able to convert these into an object graph based on the relationship which I’d added in the DBML layout. I set “Serialization” as “Unidirectional” on the layout. No issues.

The issue I had was in Serialization.  I wanted JSON from this structure. When I serialized I was getting only the top-most entry. So I stepped through the debugger and found I was getting ALL the entries when stepping through. Running the code I was getting only partial. For some reason stepping through the code forced .NET to instantiate the full object graph but I could not figure out why.

My initial thought was that L2S was doing some lazy-loading of the data but that made no sense since the stored function was retrieving all the rows in one shot.  I couldn’t figure it out.

In the end, since performance is not an issue (this is a design-time-pre-compiled bit of JSON I’m generating) I added a simple function to recursively iterate each node :

public static void ParseObj(node s){
foreach (node v in s.children)
{
// do nothing
ParseObj(v);
}

I did experiment with LoadOptions and also made sure Delay Loading was turned off but these made no difference (as expected). Weird and possibly a bug.