var ids = db.getCollection('projects').find({"format" : "Animated Instagram", "group" : "AN", "updatedAt" :
{$gt: new Date("2018-07-31")}}).limit(50).toArray().map(function(id)
{ return id._id})
printjson(ids)
db.getCollection('projects').update({_id: {$in: ids}}, {$set: {"format" : "Animated Post"}})