[{"_id":1,"name":"C:"},{"_id":2,"parentFolderId":1,"name":"Users"},{"_id":3,"parentFolderId":2,"name":"<username>"},{"_id":4,"parentFolderId":3,"name":"Desktop"},{"_id":5,"parentFolderId":4,"name":"alpha.tsx"},{"_id":6,"parentFolderId":1,"name":"Program Files"},{"_id":7,"parentFolderId":1,"name":"System32"},{"_id":8,"parentFolderId":"1","name":"Program Files(x86)"}]

db.collection.aggregate([{"$match":{name:"C:"}},{"$lookup":{"from":"collection","localField":"_id","foreignField":"parentFolderId","as":"parents"}},{"$unwind":"$parents"},{"$replaceRoot":{"newRoot":"$parents"}},{$set:{tags:["new","nice"]}}])