NHibernate: How to insert a new Set member after containing object is created?

Question

I have a Person class which has a Tags property

public virtual System.Collections.Generic.List<Tag> Tags { get; set; }

which contains a collection of Tag class objects.

Given the system design, the instance of the Person class is created initially and then at a later time the user can add tags to a Person.

Being new to NHibernate I can figure out how to add one or more tags to the existing person object. Do I need to retrieve the Person object then Add() one or more new Tag objects? There may also already be Tag objects in the List.

Same question related to removing an existing Tag object in the Tags collection.

Thanks

Answer 1

If the Tag knows which person it belongs to you could do:

var person = session.Load<Person>(id);
var tag = new Tag() { Person = person; /* stuff */ };
session.Save(tag);

session.Flush();

This should avoid doing a query on person.

I also think you'll need to change Tags to IList.

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Edit:

Moved other example... I don't think it would avoid a select query.

var person = session.Load<Person>(id);
person.Tags.Add(new Tag() { /* stuff */ };

session.Flush();

I'm not sure if accessing Tags will force the object to be instantiated?