Hi, i have an array like this array: [0,1,2,4,5,7,86,4,32,3,4] i need to assign a key to them all like the result will be: array: [{“key”: 0}, {“Key”:1},… so on to all. by Aggregation only. thanks

[image] Brutal_Jazzy: the only problem this aggregate has it doesn’t copy the old values db.collection.aggregate([ { $unwind: "$a" }, { $group: { _id: { _id: "$_id", a: "$a" }, doc: { $first: "$$ROOT" }, count: { $sum: 1 } } }, { $group: { _id: "$_id._…