[{"genres":"[{'id': 16, 'name': 'Animation'}, {'id': 35, 'name': 'Comedy'}, {'id': 10751,'name': 'Family'}]"}]

db.collection.aggregate([{"$project":{"genres":{"$function":{"body":"function(genres) { genres = genres.replace(/'/g, '\"'); return JSON.parse(genres) }","args":["$genres"],"lang":"js"}}}},{"$merge":{"into":"collectionName","on":"_id","whenMatched":"replace","whenNotMatched":"insert"}}])