Linq to SQL and Serialization : A circular reference was detected while serializing an object of type [whatever]

Okay so I created a Linq to SQL model today. It includes tables for Blog Posts and Blog Comments which have a one-to-many relationship, hence a BlogComment has a .BlogPost property and a BlogPost has a .BlogComments property. Pretty standard.

When I attempted to serialize a collection of BlogPosts and their related BlogComments I was met with the following error:

A circular reference was detected while serializing an object of type BlogPost.

Fairly obvious why – the serializer is working through each property on a BlogPost using reflection, then enumerating each comment on the blog post, enumerating each property on the comment which includes a reference back to the blog post – which is where the circular reference joins up.

Obvious problem, but how to get around it? What I actually need to do is instruct the XmlSerializer to ignore the BlogComment.BlogPost property – I want it to enumerate the comments attached to a blog post but I don’t want it to walk back up to the blog post. To accomplish this I don’t want to have to mess with my DBML file or the C# class definitions, because as soon as I modify the database in the future I’ll have to reimplement those changes. A partial class implementation won’t help me because I need to modify the original class, not patch new functionality onto it. I was thinking I needed to add an [XmlIgnore] attribute somewhere, and that this would be a nightmare.

Well it turns a much simpler solution is to just mark the relationship as an Internal property in the Linq to SQL designer.

This works because the XmlSerializer only serializes public properties.