[{"_id":"1","name":"Valerio","gender":"M","favorites":[]},{"_id":"2","name":"Samad","gender":"M","favorites":["1","3","4"]},{"_id":"3","name":"Ayub","gender":"F","favorites":["1","4"]},{"_id":"4","name":"Apour","gender":"M","favorites":["2"]}]

db.collection.aggregate([{"$addFields":{"searchElemExists":{"$cond":{"if":{"$in":["1","$favorites"]},"then":1,"else":0}}},},{"$sort":{"searchElemExists":-1}},{"$project":{"searchElemExists":0,},},])