对于给定的文档，如何在mongodb中更新和重命名字段？

db.collection.update(
   <query>,
   <update>,
   {
     upsert: <boolean>,
     multi: <boolean>,
     writeConcern: <document>
   }
)

{
   "_id": 1,
   "name": "John",
   "age": 30
}

db.users.update(
   { "_id": 1 },
   { $set: { "age": 31 } }
)

db.collection.update(
   <query>,
   { $rename: { <oldFieldName>: <newFieldName> } },
   {
     upsert: <boolean>,
     multi: <boolean>,
     writeConcern: <document>
   }
)

db.users.update(
   { "_id": 1 },
   { $rename: { "age": "newAge" } }
)