用Mongodb將一個元素推到一個數組中的陣列

Question

你好，我對mongodb相當陌生，誠實，因爲我習慣於使用mysql，並且對json的熟悉程度也較低。

這裏是從集合討論

{ 
     "_id" : ObjectId("5188c93f0361ca6dc33e3a30"), 
     "admin" : [ ], 
     "created" : "2013-04-30 19:10:21", 
     "description" : "guitar theory", 
     "members" : [ ], 
     "modified" : "2013-04-30 19:10:21", 
     "name" : "Arpeggios", 
     "posts" : [ 
       { 
         "post_id" : "1", 
         "user_id" : "1", 
         "name" : "Test", 
         "slug" : "xxx", 
         "comment" : "xxx", 
         "created" : "xxx", 
         "modified" : "xxx", 
         "comments" : [ ], 
         "attachments" : [ ] 
       }, 
       { 
         "post_id" : "2", 
         "user_id" : "1", 
         "name" : "Test", 
         "slug" : "xxx", 
         "comment" : "xxx", 
         "created" : "xxx", 
         "modified" : "xxx", 
         "comments" : [ ], 
         "attachments" : [ ] 
       } 
     ], 
     "profile_pic" : "adasdad", 
     "settings" : [ ], 
     "slug" : "arpeggio" 
} 

我的目標是要在其上POST_ID = 1的陣列註釋推的元素，讓畫面是這樣的結果，我的文檔我想：

{ 
     "_id" : ObjectId("5188c93f0361ca6dc33e3a30"), 
     "admin" : [ ], 
     "created" : "2013-04-30 19:10:21", 
     "description" : "guitar theory", 
     "members" : [ ], 
     "modified" : "2013-04-30 19:10:21", 
     "name" : "Arpeggios", 
     "posts" : [ 
       { 
         "post_id" : "1", 
         "user_id" : "1", 
         "name" : "Test", 
         "slug" : "xxx", 
         "comment" : "xxx", 
         "created" : "xxx", 
         "modified" : "xxx", 
         "comments" : [ 
         {"comment_id":"xxx", "user_id":"xxx", "name":"xxx","comment":"xxx", "created":"xxx", "modified":"xxx"}, 
         {"comment_id":"xxx", "user_id":"xxx", "name":"xxx","comment":"xxx", "created":"xxx", "modified":"xxx"} 
         ], 
         "attachments" : [ ] 
       }, 
       { 
         "post_id" : "2", 
         "user_id" : "1", 
         "name" : "Test", 
         "slug" : "xxx", 
         "comment" : "xxx", 
         "created" : "xxx", 
         "modified" : "xxx", 
         "comments" : [ ], 
         "attachments" : [ ] 
       } 
     ], 
     "profile_pic" : "adasdad", 
     "settings" : [ ], 
     "slug" : "arpeggio" 
} 

我已經徹底研究了幾個小時已經，這是我想出了這僅僅是一個失敗並不起作用：

db.discussions.update(
       {_id:ObjectId("5188c93f0361ca6dc33e3a30"), posts:{post_id:1}}, 
       {$push: 
        {"posts: 
         {comments: 
          {"comment_id":"xxx", "user_id":"xxx", "name":"xxx","comment":"xxx", "created":"xxx", "modified":"xxx"} 
         } 
        } 
       } 
       ) 

請大家我拼命地尋求幫助。我想了解這一點。

Answer 1

有幾件事情正在進行。

首先你想使用the $ positional operator。

其次，你提到你的集合名稱是Discussion，但是你的更新使用「討論」 - 確保你使用與實際集合名稱相同的名稱。

第三，您列出的文檔中的post_id是「1」，但您試圖匹配1.字符串「1」不會等於數字1.請注意您的類型。

這句法（注意我也糾正不平衡報價）應該這樣做：

db.discussion.update(
      {_id:ObjectId("5188c93f0361ca6dc33e3a30"), "posts.post_id":"1"}, 
      {$push: 
        {"posts.$.comments": 
         {"comment_id":"xxx", "user_id":"xxx", 
          "name":"xxx","comment":"xxx", "created":"xxx", 
          "modified":"xxx"} 
        } 
       } 
      ) 

我要重申，我對這個模式的厭惡 - 你是不是邊界您的文檔的增長，這將導致性能問題，更不用說使它比你需要的更復雜（也更大）。