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db.collection.aggregate([{"$unwind":"$item"},{$project:{"item.adjudication":{"$map":{"input":"$item.adjudication","in":{amount:"$$this.amount.value",code:{"$arrayElemAt":["$$this.category.coding",0]}}}}}},{$project:{"item.adjudication":{"$map":{"input":"$item.adjudication","in":{v:"$$this.amount",k:{"$let":{"vars":{"code":{"$split":["$$this.code.code","/"]}},"in":{"$arrayElemAt":["$$code",-1]}}}}}}}},{$project:{"item.adjudication":{"$arrayToObject":"$item.adjudication"}}},{"$group":{"_id":"$_id","item":{"$push":"$item"}}}])