[{"collection":"Students","count":100,"content":{"student_id":{"type":"autoincrement","autoType":"int","start":0},"grades":{"type":"stringFromParts","parts":[{"type":"enum","randomOrder":true,"values":["A","B","C","D","E","F"]},{"type":"enum","randomOrder":true,"values":["+","-",""]}]},"student_name":{"type":"faker","method":"FirstName"}}}]

db.Students.aggregate([{"$group":{"_id":"$grades","names":{"$push":"$student_name"},"count":{"$count":{}}}}])