如何在MongoDB聚合中添加自动递增字段? [英] How to add auto incrementing field in MongoDB aggregate?

问题描述

我想添加一个附加的键号，该键号包含自动递增号的值.我怎样才能做到这一点?下面是查询.无需进行展开和分组是否可以实现此结果?

I want to add an additional key number which holds a value of the auto-incrementing number. How can I achieve this? Below is the query. Is it possible to achieve this result without doing unwind and group?

[
   {
      "$match":{
         "iContestId":"5e4118161a7b5765ee9b40ef"
      }
   },
   {
      "$project":{
         "_id":"$_id",
         "nPointsEarned":"$nPointsEarned",
         "iContestId":"$iContestId",
         "iUserId":"$iUserId",
         "ranking":"$ranking",
         "sFullName":"$sFullName",
         "sProfilePicture":"$sImage",
         "nAutoIncrement": {
             "$count": {
                 "$sum": 1
             }
         }
      }
   },
   {
      "$sort":{
         "ranking":1
      }
   },
   {
      "$skip":0
   },
   {
      "$limit":23
   }
]

推荐答案

这是不可能的.没有任何运算符可以生成序列号

It's not possible. There is no any operator to generate the sequence number

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