mongodb 2.0 query by discriminator

Question

Given the following model

[BsonDiscriminator(RootClass = true)]
[BsonKnownTypes(typeof(Employee), typeof(Contractor)]
public class Person
{
    public ObjectId Id {get;set;}
    public string Name {get;set;}
}
public class Employee : Person
{
    public double Salary {get;set;}
}    
public class Contractor : Person
{
    public double DailyRate {get;set;}
}

with the legacy driver I can do the following to get a list of all contractors.

var employees = database.GetCollection("people").AsQueryable<Employee>().OfType<Employee>();

How ever at the moment the AsQueryable() is not supported in the 2.0 driver (should be out for 2.1) so in the meantime, I'm at a bit of a loss on how to construct a suitable filter for selecting all contractors from the collection

var list = await collection.Find(filter).ToListAsync();

Answer 1

Relevant feature request here: https://jira.mongodb.org/browse/CSHARP-1194

For now, you can use an "is" filter.

collection.Find(x => x is Employee).ToListAsync();

You'll still need to cast at the end into an Employee, but they will all be filtered according to the registered discriminator.