Mongoose also offers a helper method for finding a subdocument by ID. Given an
array of subdocuments Mongoose has an id method that accepts the ID you want to
find. The id method will return the single matching subdocument, and it can be used
as follows:Loc .findById(req.params.locationid) .select('name reviews') .exec(function(err, location) { var review; review = location.reviews.id(req.params.reviewid); } );