Converting Nhibernate Object to JSON

Question

I am getting this error while I am converting.

Initializing[Entity.Tag#8]-failed to lazily initialize a collection of role: Entity.Tag.Feed, no session or session was closed

Feed feed = new Feed();

Tag tag = Tag.READ.ById(8);
feed.Tag.Add(tag);
feed.Language = ENLanguage.EN;
feed.Name = "Foo";

feed.Save();

string x = JsonConvert.SerializeObject(feed);

Feed Class

public class Feed : BaseClass<Feed>
{
    public virtual int FeedId { get; set; }
    public virtual IList<Tag> Tag { get; set; }
    public virtual ENLanguage Language { get; set; }
    public virtual string Name { get; set; }

    public Feed()
    {
        Tag = new List<Tag>();
    }

    public virtual void AddTag(Tag tag)
    {
        tag.Feed.Add(this);
        Tag.Add(tag);
    }
}

Feed Map

public class FeedMap : ClassMap<Feed>
{
    public FeedMap()
    {
        Id(x => x.FeedId);
        HasManyToMany(x => x.Tag).Cascade.All().Table("FeedTag");
        Map(x => x.Language).CustomType<short>();
        Map(x => x.Name);
    }
}

Tag Class

public class Tag : BaseClass<Tag>
{
    public virtual int TagId { get; set; }
    public virtual IList<Feed> Feed { get; protected set; }
    public virtual string Name { get; set; }
}

Tag Map

public class TagMap : ClassMap<Tag>
{
    public TagMap()
    {
        Id(x => x.TagId);
        Map(x => x.Name);
        HasManyToMany(x => x.Feed).Cascade.All().Inverse().Table("FeedTag");
    }
}

Save Method

    using (var session = NHibernateHelper.OpenSession())
    {
        using (var transaction = session.BeginTransaction())
        {
            session.SaveOrUpdate(x);

            transaction.Commit();
        }
    }

Where's you session starting and ending? I've had that problem before when I've loaded something in the controller, but when the view trys to do something with it, the session is closed. — Keith Nicholas
– Keith Nicholas, Commented Sep 14, 2014 at 20:34
I think you are asking for save method? I added to question. — Mert
– Mert, Commented Sep 14, 2014 at 20:37
oh! you are closing the session straight away..... that means it can't lazy load things later — Keith Nicholas
– Keith Nicholas, Commented Sep 14, 2014 at 20:42
I am not familiar with nhibernate, what should be the right way to do? — Mert
– Mert, Commented Sep 14, 2014 at 20:44

Keith Nicholas · Accepted Answer · 2014-09-14 21:16:25Z

2

Sounds like your session is ended too quickly. You only open it for your save.

try

using (var session = NHibernateHelper.OpenSession())
{
  Feed feed = new Feed();

  Tag tag = Tag.READ.ById(8);
  feed.Tag.Add(tag);
  feed.Language = ENLanguage.EN;
  feed.Name = "Foo";

  feed.Save();

  string x = JsonConvert.SerializeObject(feed);
}

answered Sep 14, 2014 at 21:16

Keith Nicholas

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2 Comments

Mert Over a year ago

What if I only cover SerializeObject with using? does that work? If It is I am planing to create ToJson generic method which handles sessin inside it. so I could use it like "feed.ToJson()"

Mert Over a year ago

[JsonIgnore] is solved my problem but I learned something new from you guys! appreciated!

Roman G. · Accepted Answer · 2014-09-14 20:58:20Z

1

I think your problem that you don't initialize lazy collection IList Feed of class Tag when you get object from database

Tag.READ.ById(8); // in that method you have to initialize Feed

something like

using(session = NHibernateHelper.OpenSession())
{
var TagObjectFromDb = session.Get<Tag>(id);
NHibernateUtil.Initialize(TagObjectFromDb.Feed);//initialize lazy collection, 
return TagObjectFromDb;
}

and

Feed fbfeed = new Feed();//fbfeed - typo?

Tag tag = Tag.READ.ById(8);
feed.Tag.Add(tag);//fbfeed - typo?

edited Sep 14, 2014 at 20:58

answered Sep 14, 2014 at 20:51

Roman G.

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4 Comments

Mert Over a year ago

READ.ById is a generic method. What you are suggesting is not suitable. any way around?

Roman G. Over a year ago

when you call string x = JsonConvert.SerializeObject(feed); instance feed must by fully initialized. For collection properties like IList<Feed> Feed or IList<Tag> Tag you have to call NHibernateUtil.Initialize() inside opened session

Roman G. Over a year ago

In your case i can think of simple solution,since you don't have opened session, which you could use to initialize collection. Or maybe you have but i can't see that in your example.

Mert Over a year ago

[JsonIgnore] is solved my problem but I learned something new from you guys! appreciated!

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