How does mongoose continue to query from the array of queries?

  mongodb, question
User.find({follow:true}).exec(function(err,objs){
 How should it be written here?
 Follow.find({_id:{$in:objs.followId}})
 })

I want to get a lot of ids through a query, and then use these ids to get another set of data.

Is there any direct method? Do you still have to cycle through all the followId in objs?