How could I do the following in mongo?
db.questions.find( { _id: { $in: [ "506b422ff42c95000e000004", "506b422ff42c95000e00007a", "506b422ff42c95000e00008d"] } } ).sort( {_id: { $in: [ "506b422ff42c95000e00007a", "506b422ff42c95000e00008d", "506b422ff42c95000e000004"]}});
Is it even possible or do I have to do this on the code end?
No, not really. You'll need to do that yourself. The results won't come back in the order you construct your query. See this similar question: Order of responses to MongoDB $in query?
Your ID's do look numerically ordered though and they're based on date, so you could sort on _id itself, but there's no way of even determining if those objects would even be stored in that order in the database.
