如何把項目限制在rethinkdb

Question

我在rethinkdb中有很多字段和項目的表，我想獲取所有數據，但這個表中的項目我只想要最後2個記錄：查看結果和查詢

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

，並顯示：

{ 
    "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 
     } 
    ] 
} 

，但我想，只顯示子的最後2項： 「MSG」 表現出一定喜歡它：

{ 
    "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 
     } 
    ] 
} 

我怎麼可能，我已經搜查瞭解決它在互聯網上，但我什麼都不匹配

Answer 1

您可以將.merge(function(row) { return {msg: row('msg').slice(-2)}; })添加到您的查詢結束。