如何将文档附加到子文档数组中 - Java/MongoDB [英] How to append document into sub-document array - Java/MongoDB

问题描述

如何使用 Java 将新文档附加到 MongoDB 上的子文档数组?

How can I append a new document to sub-document array on MongoDB with Java?

例如，将 {tweetId : 456} 附加到文档tweets"数组:

For exemple, append {tweetId : 456} to the array of documents "tweets":

{
  day : 20170209,
  hours : { 
            hour : 20,
            tweets : {tweetId : 123 }
          }     
}

想要的结果:

{
  day : 20170209,
  hours : [ {hour : 20,
             tweets : [{tweetId : 123},{tweetId : 456}]},
            {hour : 21,
             tweets : [{tweetId : 567},{tweetId : 890}]}  
          ]     
}

更新

对不起，我没有正确解释，tweet 文档是一个 tweetsId 数组.我修正了上面的例子以便更好地理解.

Sorry, I didn't explain correctly, the tweets document is an Array of tweetsId. I fixed the above example to better understanding.

例如，只有 2 个级别的集合:

For example, with a collection with only 2 levels:

{  
   "_id":{  
      "$oid":"589c5a1047e9062f004b84a3"
   },
   "hashtag":"BRASIL",
   "tweets":[  
      {  
         "tweetId":"829661297121845249"
      },
      {  
         "tweetId":"829661278352269313"
      }
   ]
}

我可以将一个新的 TweetId 附加到这个数组:

I can append a new TweetId to this array with:

collection.updateOne(new Document("hashtag", hashtag),
                    new Document("$push", new Document("tweets", new Document("tweetId", tweetId))));

但是当数组处于第 3 级(小时 > 推文 > TweetId)时，我找不到正确的方法.

But when the array is at level 3 (Hours > Tweets > TweetId), I can't find a way to do it correctly.

希望现在解释得更好.

推荐答案

通过 Riccardo 发送的提示，我查看了如何使用聚合函数并能够获得我需要的结果，而无需按小时为推文创建集合.

with the tip sent by Riccardo, I look how to use the aggregation function and was able to get the result that I needed without creating a collection for tweets by hour.

我使用了包含所有推文及其详细信息的集合，并使用以下函数检索数据:

I used the collection that had all the tweets with its details, and with the function below, was able to retrieve the data:

tweetsCol.aggregate([
                     {$group: {_id : {Date : "$date", Hour : '$hour'}, Total : {$sum : 1}}}
                    ])

我的推文集包含以下信息:

My collection of tweets has the following information:

"tweetId" : String,
"userId" : String,
"username" : String,
"followers" : String,
"language" : String,
"fulldate" : String,
"date" : String,
"hour" : String,
"text" : String,
"hashtags" : [{
    "tweetId" : String
 }]

查询结果:

[{Date : 20170209,
 hours : [{hour : 21, Total: 45},
          {hour : 22, Total: 22}]},
 {Date : 20170210,
 hours : [{hour : 11, Total: 38},
           hour : 17, Total : 71}]
]

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