Using the MongoDB Aggregation framework to count the total number of likes among all users within a collection

mostLikedUsers.js

db.users.aggregate( 
  [ 
    { $unwind : "$likes" }, 
    { $group : { _id : "$likes", number : { $sum : 1 } } },
    { $sort : { number : -1 } }, 
    { $limit : 10 }
  ] 
);

mostLikedUsersResult.json

{
  "result" : [
  {
    "_id" : "mcei5Ycf9Fv3MMcfE",
    "number" : 13
    },
    {
      "_id" : "TFXdgcLcpRJaLcTrC",
      "number" : 12
    },
    {
      "_id" : "bzvPFrsqypBsM4otx",
      "number" : 12
    }
  ],
  "ok" : 1
}

schema.json

{ "_id" : "LGWEH8eGsPqYfvFm5", 
  "profile" : { 
  	"firstName" : "Spencer", 
  	"headline" : "Web Application Developer", 
  	"lastName" : "Norman" 
  },
  "dislikes" : [
  	"5hkWyLEBNTdrbFuko", 
  	"QpKhWgFPcteYrz4CF",
  	"Ye6JFr6es5w7wCAPG",
  	"2nxJh8LP6YdtaRhoB",
  	"8hiRMNctzauggqgca",
  	"W4WHDuvFzQ8ETf8LB",
  	"YJfpzNj6b7YtN4ALa",
  	"LZnKWfsnhz5ex9apJ",
  	"KpsD84DvAHb2kaCiE",
  	"B3DF2EwqzYFNChY3d",
  	"u2n4grwb37dx44hgo",
  	"iK9LFefZHNqxFe6s7" 
  ], 
  "likes" : [ 
  	"stWyympYqtDFH2Myh",
  	"jZiZ6gi4fFcRi3Gga",
  	"5suDFYZkK4zWvtrsq",
  	"hRqFZxALzXr2DthsZ",
  	"MLkfG5K69oJGz6A5a",
  	"yF2yQgeDWaMFxqvWe",
  	"g3sa2onpPRuZYfYvN"
  ]
}

totalDislikes.js

db.users.aggregate( 
  [ 
    { $unwind : "$dislikes" }, 
    { $group : { _id : null, number : { $sum : 1 } } } 
  ] 
);

totalLikes.js

db.users.aggregate( 
  [ 
    { $unwind : "$likes" }, 
    { $group : { _id : null, number : { $sum : 1 } } } 
  ] 
);