Linq for NHibernate and fetch mode of eager loading

Question

Is there a way to set the fetchmode to eager for more than one object using linq for nhibernate. There seems to be an expand method which only allows me to set one object. However I need to set it for more than one object. Is this possible? Thanks

Endo

Answer 1

just use it more then once.

IList<Entity> GetDataFromDatabase()
{
    var query = session.Linq<Entity>();
    query.Expand("Property1");
    query.Expand("Property2");
    return query.ToList();
}

Oteliaotero

or query.Expand("Property1,Property2"); – Mooring

Is that an expansion method? Can't find it in NHibernate.Linq v2.0.50727. – Welldressed

It is there, on NHibernate.Linq.Query<T> – Linen

Answer 2

The new Linq provider does it a little differently:

var customers = session.Query<Customer>().Fetch(c => c.Orders).ToList();

More here: http://mikehadlow.blogspot.com/2010/08/nhibernate-linq-eager-fetching.html

Igniter

if Orders has a sub class of its own, would it load eagerly? if not - how would you change the query to load it? – Wedding

To get grandchilds: var customers = session.Query<Customer>() .FetchMany(c => c.Orders) .ThenFetchMany(o => o.OrderLines).ToList(); – Wedding

Answer 3

As far as I can see, this is not equivalent: SetFetchMode hydrates an objects tree and the Expand method retrieves a cartesian product.

Generally

Answer 4

In contiune to @Mike Hadlow answer, fetching next level (grandchildren) you need to do:

var customers = session.Query<Customer>() .FetchMany(c => c.Orders) .ThenFetchMany(o => o.OrderLines).ToList();

Wedding