[{"createdAt":"2020/10/10","passCheck":"success"},{"createdAt":"2020/10/10","passCheck":"failure"},{"createdAt":"2020/10/10","passCheck":"success"},{"createdAt":"2020/10/10","passCheck":"failure"},{"createdAt":"2020/10/11","passCheck":"success"},{"createdAt":"2020/10/11","passCheck":"success"}]

db.collection.aggregate([{$group:{"_id":{"year":{$substr:["$createdAt",0,4]},"month":{$substr:["$createdAt",5,2]},"day":{$substr:["$createdAt",8,2]}},"success_count":{$sum:{$cond:[{$eq:["$passCheck","success"]},1,0]}},"failure_count":{$sum:{$cond:[{$eq:["$passCheck","failure"]},1,0]}}}},{"$addFields":{"_id.failure_count":"$failure_count","_id.success_count":"$success_count","failure_count":"$$REMOVE","success_count":"$$REMOVE"}}])