RavenDb Indexes : 1st Attempt

I’ve been playing with RavenDb’s pre-defined indexes today. They use a map reduce model with Linq, which is very nice. A recent new feature is the ability to define them in your application code. Here a couple I’ve just created:

public class Child_ByName : AbstractIndexCreationTask<Child>
{
    public Child_ByName()
    {
        Map = children => from child in children
                          select new { child.Name };
    }
}

public class Child_ByPendingSchedule : AbstractIndexCreationTask<Child>
{
    public Child_ByPendingSchedule()
    {
        Map = children => from child in children
                          from schedule in child.Account.PaymentSchedules
                          select new { schedule.NextRun };
    }
}

You register them with the RavenDb document store (a bit like a session factory in NHibernate) like this:

IndexCreation.CreateIndexes(typeof(Child_ByName).Assembly, store);

When you want to use them, you have to use a rather nasty magic string (RavenDb converts the underscore in the class name to a forward slash ‘/’).

var results = session.Advanced.LuceneQuery<Child>("Child/ByName").WhereEquals("Name", "two").ToList();

It would be much nicer if you could write something like this instead:

var results = session.Advanced.LuceneQuery<Child_ByName>().WhereEquals("Name", "two").ToList();

Here a couple of tests showing them at work:

[TestFixture]
public class RavenDbSchedulingWithIndex : LocalClientTest
{
    IDocumentStore store;
    Parent parent;
    DateTime now;

    [SetUp]
    public void SetUp()
    {
        store = NewDocumentStore();
        IndexCreation.CreateIndexes(typeof(Child_ByName).Assembly, store);
        parent = new Parent("Dad", "mike@mike.com", "xxx");

        now = new DateTime(2010, 4, 5);

        // create some children with accounts and schedules
        using (var session = store.OpenSession())
        {
            session.Store(CreateChildWithSchedule("one", 1M, now.AddDays(-2)));
            session.Store(CreateChildWithSchedule("two", 2M, now.AddDays(-1)));
            session.Store(CreateChildWithSchedule("three", 3M, now));
            session.Store(CreateChildWithSchedule("four", 4M, now.AddDays(1)));
            session.Store(CreateChildWithSchedule("five", 5M, now.AddDays(2)));
            session.SaveChanges();
        }
    }

    [Test]
    public void Select_child_using_ByName_index()
    {
        using (var session = store.OpenSession())
        {
            var results = session.Advanced.LuceneQuery<Child>("Child/ByName").WhereEquals("Name", "two").WaitForNonStaleResults().ToList();
            results.Count().ShouldEqual(1);
            results[0].Name.ShouldEqual("two");
        }
    }

    [Test]
    public void Select_child_using_ByPendingSchedule()
    {
        using (var session = store.OpenSession())
        {
            var results = session.Advanced
                .LuceneQuery<Child>("Child/ByPendingSchedule")
                .WhereLessThan("NextRun", now)
                .WaitForNonStaleResults().ToList();

            results.Count().ShouldEqual(2);
            results[0].Name.ShouldEqual("one");
            results[1].Name.ShouldEqual("two");
        }
    }

    Child CreateChildWithSchedule(string name, decimal amount, DateTime startDate)
    {
        var child = parent.CreateChild(name, name, "xxx");
        child.Account.AddPaymentSchedule(startDate, Interval.Week, amount, "Pocket Money");
        return child;
    }
    
}

This is some spike code from Tardis Bank. You can checkout the complete project here:

http://github.com/mikehadlow/Suteki.TardisBank