Question

I’ve got the following model:

public class Competitor
{
    public virtual int CompetitorId { get; set; }
    public virtual string TeamName { get; set; }
    public virtual string FirstName { get; set; }
    public virtual string LastName { get; set; }
    public virtual DateTime BirthDate { get; set; }

    public virtual IEnumerable<CompetitorBest> CompetitorBests { get; set; }
}


public class CompetitorBest
{
    public virtual int ResultId { get; set; }
    public virtual string BestTypeName { get; set; }
    public virtual string IndoorOutdoor { get; set; }
    public virtual int Season { get; set; }
    public virtual string DisciplineName { get; set; }
    public virtual string ResultValue { get; set; }
}

When trying to save it to my MongoDB instance, I get the following error:

Maximum serialization depth exceeded (does the object being serialized have a circular reference?).

I’m using automapping (ie- not set any class mapping)

I can’t see what could be wrong?
There’s no circular reference?

Answer 1

Ok,
I’m submitting this as an answer, mainly because it works – ie, allows me to save the document as required.

As @chebum correctly pointed out, the problem is actually with the fact I’m pulling the entities using that model using nHibernate first.
This means that my IEnumerable< CompetitorBest > on my Competitor object, is actually of type NHibernate.Collection.Generic.PersistentGenericBag

As correctly pointed out by @chebum in the comments, this will have a reference to the original object, therefore creating a circular reference.

Rather than create a mongodb class map (which is what I should probably do.. feel free to answer) this is what I did to get things working for now.

Changed my Competitor class to this:

public class Competitor
{
    private IList<CompetitorBest> _competitorBests;

    //other properties

    public virtual IEnumerable<CompetitorBest> CompetitorBests
    {
        get { return _competitorBests.ToArray(); }
        set { }
    }
}

Then in my nHibernate Class Map:

HasMany(x => x.CompetitorBests)
    .Not.LazyLoad()
    .Access.CamelCaseField(Prefix.Underscore)
    .Inverse()
    .AsBag()
    .KeyColumn("competitorId");

Again, I’m sure there’s a better way of doing it (perhaps with a mongodb class mapping??)
But i’ve added this as it works for me… for now.