Mongodb dot notation wildcard?

Question

I have a collection of users, each of which may be subscribed to one or more services. Each service has some meta data, including the number of credits the user has for that

Answer 1

I don't know of a way to accomplish this using the schema you're using. It seems to me you're abusing objects as arrays. If services were an array (the plural hints that it should be), you could simply query

db.users.find({"services.credits" : { $lt : 50 }}); 

or use $elemMatch if you need to match multiple conditions on a single array element.