Raven-WhereInTest.cs

namespace RavenDB.WhereInTest
{
    using System;
    using System.Collections.Generic;
    using System.Linq;
    using Raven.Abstractions.Data;
    using Raven.Abstractions.Indexing;
    using Raven.Client.Document;
    using Raven.Client.Embedded;
    using Raven.Client.Indexes;

    public class User
    {
        public string Id { get; set; }

        public List<string> Roles { get; set; }
    }

    public class Users_Index : AbstractIndexCreationTask<User>
    {
        public Users_Index()
        {
            Map = users => from user in users
                select new
                {
                    user.Roles
                };

            Index(x => x.Roles, FieldIndexing.NotAnalyzed);
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            using (var store = new EmbeddableDocumentStore() { RunInMemory = true }.Initialize()) 
            {
                IndexCreation.CreateIndexes(typeof(Users_Index).Assembly, store);

                using (var session = store.OpenSession())
                {
                    session.Store(new User()
                    {
                        Roles = new List<string>() { "Roles/User", "Roles/Admin" },
                    });

                    session.Store(new User()
                    {
                        Roles = new List<string>() { "Roles/User" },
                    });

                    session.SaveChanges();
                }

                using (var session = store.OpenSession())
                {
                    var query = session.Advanced.DocumentQuery<User, Users_Index>()
                        .WaitForNonStaleResults()
                        .UsingDefaultOperator(QueryOperator.And) // COMMENT THIS LINE TO MAKE IT WORK
                        .WhereIn("Roles", new[] { "Roles/Admin", "Roles/Manager" })
                        .Skip(0)
                        .Take(20)
                        .ToList();

                    Console.WriteLine($"Found {query.Count} users.");

                }
            }

            Console.Read();
        }
    }
}