Fluent nhibernate one-to-many

Question

I have a one-to-many relationship and cannot get cascade to work, once I set cascade I just get "object references an unsaved transient instance ...".

My mapping looks like this

public class SharedDetailsMapping : ClassMap<SharedDetails>
{
    public SharedDetailsMapping()
    {
        Id(x => x.Id).GeneratedBy.Identity();
        HasMany(x => x.Foos);
    }
}

public class FooMapping : ClassMap<Foo>
{
    public FooMapping()
    {
        Id(x => x.Id).GeneratedBy.Identity();
        References(x => x.SharedDetails).Cascade.SaveUpdate();
    }
}

The classes like this

public class Foo
{
    public Foo()
    {
        SharedDetails = new SharedDetails();
        SharedDetails.Foos.Add(this);
    }

    public Foo(SharedDetails sharedDetails)
    {
        SharedDetails = sharedDetails;
        SharedDetails.Foos.Add(this);
    }

    public virtual Guid Id { get; set; }
    public virtual SharedDetails SharedDetails { get; set; }
}

public class SharedDetails
{
    public SharedDetails()
    {
        Foos = new List<Foo>();
    }

    public virtual Guid Id { get; set; }
    public virtual IList<Foo> Foos { get; set; }
}

I then want to create Foos without having to save the SharedDetails first if its a new Foo, like so:

using (var transaction = _session.BeginTransaction())
{
    var shared = new SharedDetails();

    var fooOne = new Foo(shared);
    _session.SaveOrUpdate(fooOne);

    var fooTwo = new Foo(shared);
    _session.SaveOrUpdate(fooTwo);

    transaction.Commit();
}

Cannot figure out what I have done wrong, it works ofcurse if I save the SharedDetails first but that is why I have Cascade setup.

moribvndvs · Accepted Answer · 2012-10-27T09:56:49.520

6

In your SharedDetailsMapping, modify your HasMany to add .Inverse():

public class SharedDetailsMapping : ClassMap<SharedDetails>
{
    public SharedDetailsMapping()
    {
        Id(x => x.Id).GeneratedBy.Identity();
        HasMany(x => x.Foos)
           .Inverse();
    }
}

This instructs NHibernate that Foo owns the relationship, which will help it save objects in the relationship in the right order (in this case, the SharedDetails has to get saved first so we have its ID when Foo is saved).

Further info on the purpose/when to use Inverse: NHibernate's inverse - what does it really mean?

The TL;DNR version:

If you have a bidirectional relationship in your classes (HasMany on one side, References on the other), the HasMany should have .Inverse().

edited Oct 27 '12 at 09:56

answered Oct 27 '12 at 09:47

moribvndvs

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The problem is I don't want to save 'SharedDetails' first, I would like it to be automatic created when I create a 'new Foo()' and then save it. Is that not possible? – Christian Oct 27 '12 at 09:56
Changing the mapping doesn't change your example code for creating and saving. You can still do what you did in your example. This mapping change, however, helps NHibernate figure out the order in which to save them internally. – moribvndvs Oct 27 '12 at 09:59
I already tried to add 'Inverse' to but it still gives the same error. Saving the 'SharedDetails' works, but that defeats the purpose of have setup Cascade. – Christian Oct 27 '12 at 10:02
1

I made a quick application from the source you posted. I had to change the ID properties from `Guid` to `int` to match your mappings (they use the Identity generator, which would require integers), but other than that it worked successfully. What's the full text of the error you are getting? It should say which object types are involved in the error. – moribvndvs Oct 27 '12 at 10:22
Found the error, had some automapping added to the setup that should not have been there. So after adding 'Inverse' and changing the ids to 'int' it worked. Thanks a million for the help! – Christian Oct 27 '12 at 10:29

Fluent nhibernate one-to-many

1 Answers1