mongodb - MongoDB查询将时间戳与嵌套对象时间戳进行比较

Question

我有以下结构的文件：

    {
       "_id":{
          "$oid":"6145b4405df7711fe1e2f3e0"
       },
       "name":"Testing1",
       "description":"Testing Project1",
       "created_at":{
          "$date":"2021-09-18T09:41:20.985Z"
       },
       "updated_at":{
          "$date":"2021-09-18T09:41:20.985Z"
       },
       "experiments":null,
       "contributors":[
          "local"
       ],
       "tags":[
          "dev",
          "prod"
       ],
       "owner":"localhost",
       "tokens":[
          {
             "owner":"localhost",
             "created_at":{
                "$date":"2021-09-18T16:38:02.911Z"
             },
             "token":"testToken"
          }
       ]
    }
############
{
   "_id":{
      "$oid":"6145b4405df7711fe1e2f3e0"
   },
   "name":"Testing2",
   "description":"Testing Project2",
   "created_at":{
      "$date":"2021-09-18T09:41:20.985Z"
   },
   "updated_at":{
      "$date":"2021-09-18T09:41:20.985Z"
   },
   "experiments":null,
   "contributors":[
      "local"
   ],
   "tags":[
      "dev",
      "prod"
   ],
   "owner":"localhost",
   "tokens":[
      {
         "owner":"root",
         "created_at":{
            "$date":"2021-09-18T16:38:02.911Z"
         },
         "token":"rootToken"
      },
      {
         "owner":"localhost",
         "created_at":{
            "$date":"2021-09-18T16:38:02.911Z"
         },
         "token":"localToken"
      }

   ]
}

1. 如何使用带有 _id 和 tokens.owner 的 findOne 查询仅返回 token 和 created_at（不是完整的文档）。
2. 如果文档的 updated_at 大于 tokens.owner created_at 则返回 false。
3. 如果我想更新任何 tokens.owner 的令牌，那么它应该更新而不是附加到令牌对象。

我正在使用 mongodb 在 go lang 中学习 api 构建，请帮助我。

谢谢。