Database
[{"itemIds":{"12341234-1234-1234-1234-123412341234":true,"23452345-2345-2354-2345-234523452354":false,"34563456-3456-3456-3456-345634563456":true}}/** ,*{* "itemIds": [* "12341234-1234-1234-1234-123412341234",* "34563456-3456-3456-3456-345634563456"* ]* }*/]
Query
db.collection.aggregate([{"$addFields":{"itemIds":{"$map":{"input":{"$filter":{"input":{"$objectToArray":"$itemIds"},"as":"item","cond":{$eq:["$$item.v",true]}}},"as":"it","in":"$$it.k"}}}}])