如何限制rethinkdb中的项目

Question

我在 rethinkdb 中有 table，它有很多字段和项目，我想获取这个 table 的所有数据，但对于项目，我只想要最后 2 条记录：查看结果和查询

r.db('db').table('table1').filter(function(opentb1){
  return openTb1('chat').match('(user_273_1|user_1_273)')
})

并展示它：

{
  "adm":  "1" ,
  "chat":  "user_273_1" ,
  "id":  "09ce2adc-9d49-4830-9fb6-fb7159f92d08" ,
  "msg": [
      {
          "date":  "2016-07-20T01:43:06.302Z" ,
          "id":  "4e1d85e0-4e1b-11e6-bb9f-2bb985f41f5d" ,
          "msg":  "sgzsrgz" ,
          "nick":  "SonickSeven" ,
          "user":  "1"
      } ,
      {
          "date":  "2016-07-20T01:43:08.832Z" ,
          "id":  "4f9f9200-4e1b-11e6-bb9f-2bb985f41f5d" ,
          "msg":  "egser" ,
          "nick":  "SonickSeven" ,
          "user":  "1"
      } ,
      {
          "date":  "2016-07-20T01:43:55.233Z" ,
          "id":  "6b47cd10-4e1b-11e6-bb9f-2bb985f41f5d" ,
          "msg":  "sergse" ,
          "nick":  "SonickSeven" ,
          "user":  "1"
      }
  ],
  "optChat": [
      {
      "height": 0 ,
      "minizar": true ,
      "position": false ,
      "user":  "1" ,
      "user2":  "273" ,
      "width": 0 ,
      "x": 0 ,
      "y": 0
      }
  ]
}

但我希望只显示子字段中的最后 2 个项目："msg" 显示类似的项目：

{
  "adm":  "1" ,
  "chat":  "user_273_1" ,
  "id":  "09ce2adc-9d49-4830-9fb6-fb7159f92d08" ,
  "msg": [
      {
          "date":  "2016-07-20T01:43:08.832Z" ,
          "id":  "4f9f9200-4e1b-11e6-bb9f-2bb985f41f5d" ,
          "msg":  "egser" ,
          "nick":  "SonickSeven" ,
          "user":  "1"
      } ,
      {
          "date":  "2016-07-20T01:43:55.233Z" ,
          "id":  "6b47cd10-4e1b-11e6-bb9f-2bb985f41f5d" ,
          "msg":  "sergse" ,
          "nick":  "SonickSeven" ,
          "user":  "1"
      }
  ],
  "optChat": [
      {
      "height": 0 ,
      "minizar": true ,
      "position": false ,
      "user":  "1" ,
      "user2":  "273" ,
      "width": 0 ,
      "x": 0 ,
      "y": 0
      }
  ]
}

我怎么可能，我已经在互联网上搜索过这个解决方案，但我什么都不匹配

Answer 1

您可以在查询的末尾添加 .merge(function(row) { return {msg: row('msg').slice(-2)}; })。

如何限制rethinkdb中的项目

how put limit to items in rethinkdb

javascript

rethinkdb

nosql