How to ignore a property during serialization for RavenDB

Using RavenDB 6, how do I prevent the serialization of a specific property to the database. I've tried [JsonIgnore], but it doesn't work.

Using [JsonIgnore] should work for you.
For example, this simple test passes with RavenDB v6.0

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

            [JsonIgnore] // Newtonsoft.Json.JsonIgnore
            public string PropToIgnore { get; set; }
        }
        
        [Fact]
        public void Test()
        {
            var store = new DocumentStore
            {
                 Urls = new[] { "http://localhost:8080"},
                 Database = "myDb"
            };
            store.Initialize();
            
            using (store)
            {
                using (var session = store.OpenSession())
                {
                    var user = new User()
                    { 
                        Name = "myName",
                        PropToIgnore = "someText"
                    };

                    session.Store(user, "Users/1");
                    session.SaveChanges();
                }
                
                using (var session = store.OpenSession())
                {
                    User testUser = session.Load<User>("Users/1");
                    Assert.True(testUser.PropToIgnore == null);
                    // The PropToIgnore property was not stored on disk
                    // and comes back as null.
                }
            }
        }