用Mongodb将一个元素推到一个数组中的阵列

Question

你好，我对mongodb相当陌生，诚实，因为我习惯于使用mysql，并且对json的熟悉程度也较低。

这里是从集合讨论

{ 
     "_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" 
} 

我的目标是要在其上POST_ID = 1的阵列注释推的元素，让画面是这样的结果，我的文档我想：

{ 
     "_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" 
} 

我已经彻底研究了几个小时已经，这是我想出了这仅仅是一个失败并不起作用：

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"} 
         } 
        } 
       } 
       ) 

请大家我拼命地寻求帮助。我想了解这一点。

Answer 1

有几件事情正在进行。

首先你想使用the $ positional operator。

其次，你提到你的集合名称是Discussion，但是你的更新使用“讨论” - 确保你使用与实际集合名称相同的名称。

第三，您列出的文档中的post_id是“1”，但您试图匹配1.字符串“1”不会等于数字1.请注意您的类型。

这句法（注意我也纠正不平衡报价）应该这样做：

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，我对这个模式的厌恶 - 你是不是边界您的文档的增长，这将导致性能问题，更不用说使它比你需要的更复杂（也更大）。