MongoDB - 在结果集中过滤内部数组的内容 [英] MongoDB - Filtering the content of an internal Array in a resultset

问题描述

我是使用MongoDB的新手，我不知道如何解决下一个问题：

我有这样的文档集合：

  {
URL：www.stackoverflow.com，
TAGS：[
 {NAME：question，VOTES：3}，
 {NAME：answer，VOTES：5}，
 {NAME：problem， VOTES：2} 
] 
} 
  

首先，我想要列表中列出所有标签的所有Url。
我通过quering解决了这个问题：

  db.links.find（{Tags.Name：{$ all：[question，answers]}}）; 
  

但是，这个查询返回整个正确的文档，insted只有正确的文档，只有我有标签我要找的结果是：

  {
URL：www.stackoverflow.com，
TAGS：[{NAME：question，VOTES：3}，
 {NAME ：answer，VOTES：5}] 
} 
  

  {
URL：www.stackoverflow.com，
TAGS：[ {NAME：question，VOTES：3}，
 {NAME：answer，VOTES：5}，
 {NAME VOTES：2}] 
} 
  

因为我只要求标签[ 问题，答案]。

我想过使用MapReduce或解析结果集，但是我不知道是否解决问题的正确方法。也许有一个内置函数可以更有效地解决它。

谢谢！

解决方案

感谢Robert。我意识到，我正在寻找的功能目前尚未实现。以下是问题的链接。我希望MongoDB能够在短时间内实现它。谢谢！

I'm new using MongoDB, and I don't know how to solve the next problem:

I have a collection of documents like this:

{
 "URL": "www.stackoverflow.com",
 "TAGS": [
         {"NAME": "question", "VOTES": 3},
         {"NAME": "answer", "VOTES": 5},
         {"NAME": "problem", "VOTES": 2}
         ]
}

First of all, I wanted all the Urls that have all the tags given in a list. I have solved this by quering:

db.links.find( { "Tags.Name" : { $all: ["question","answers"] } } );

But this query return the whole correct document, insted of only the correct document with only the tags I have asked for.

The result I'm looking for is:

{
 "URL": "www.stackoverflow.com",
 "TAGS": [{"NAME": "question", "VOTES": 3},
         {"NAME": "answer", "VOTES": 5}]
}

and not:

{
 "URL": "www.stackoverflow.com",
 "TAGS": [{"NAME": "question", "VOTES": 3},
         {"NAME": "answer", "VOTES": 5},
         {"NAME": "problem", "VOTES": 2}]
}

Because I've only asked for the tags ["question","answers"].

I thought about using MapReduce or parsing the resultset, but I don't know if it is the correct way of solving the problem. Maybe there is a builtin function that solve it more efficiently.

Thanks!

解决方案

Thanks Robert. I have realized that the featured I'm looking for is not implemented at this moment. Here is the link of the issue. I hope that the MongoDB cominuty implements it in a short time. Thanks!

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