I got into some weird problem. I am on rails 3.1.1 and using mongoid 2.3.3
Here is what I did. When I did: @line.stations.asc(:created_at).to_a returned [#<WorkStation _id: 4ec5ecd3cf6e890e3a00001e, _type: "WorkStation", created_at: 2011-11-18 05:27:47 UTC, updated_at: 2011-11-18 05:27:47 UTC, deleted_at: nil, index: 1, batch_size: 1, line_id: BSON::ObjectId('4ec5ecd3cf6e890e3a00001b')>]
Its fine and now I just want it in json format with only _type field so did @line.stations.asc(:created_at).to_a.to_json(:only => :_type)
which do works fine in development environment but when in test environment, to_json(:only => :_type) did gave output in json format but the filter in not working. That means it didn't had any effect of putting :only => :_type in it. It just returns json output with the whole fields.
I am thinking is it due to to_a method calling before to_json (which works fine in development). Because @line.stations.asc(:created_at).to_json(:only => :_type) does the work.
So the problem is filter does not works if I did @line.stations.asc(:created_at).to_a.to_json(:only => :_type) and works if I did @line.stations.asc(:created_at).to_json(:only => :_type) . And remember this happens only in test env. Both ways are working fine in development environment.