mongodb-聚合 - 如何分组，连接阵列，单个步骤中的总体字段

Question

我有一个称为“ session_list”的集合，其中包括以下行。

{"user_id":"[email protected]","focus_score":[1, 2, 3, 4],"active_score":[3, 4, 1], "score" : 10}
{"user_id":"[email protected]","focus_score":[3, 4],"active_score":[3, 4, 1, 7, 7], "score" : 3}
{"user_id":"[email protected]","focus_score":[1, 2, 3, 4, 7],"active_score":[3, 9, 2], "score" : 7}
{"user_id":"[email protected]","focus_score":[5, 7, 8],"active_score":[1, 3, 7], "score" : 4}

如何按USER_ID进行分组，并合并fuse_score数组，然后巩固Active_score数组（没有任何循环）？

预期结果：

{"user_id":"[email protected]","focus_score":[1, 2, 3, 4, 1, 2, 3, 4, 7], "active_score":[3, 4, 1, 3, 9, 2], "score_sum" : 17}
{"user_id":"[email protected]","focus_score":[3, 4, 5, 7, 8], "active_score":[3, 4, 1, 7, 7, 1, 3, 7], "score_sum" : 7}

我的代码：

db.session_list.aggregate([
        {
            $group: {
              _id:{user_id:'$user_id'},
              focus_score:{$push:'$focus_score'}
              active_score:{$push:'$active_score'}
              score_sum:{$sum:'$score_sum'}
            }
        }
    ])

但这并不能提供预期的结果。

Answer 1

db.collection.aggregate([
  {
    $group: {
      _id: "$user_id",
      focus_score: { $push: "$focus_score" },
      active_score: { $push: "$active_score" },
      score_sum: { $sum: "$score" }
    }
  },
  {
    $project: {
      _id: 0,
      score_sum: 1,
      user_id: "$_id",
      focus_score: {
        $reduce: {
          input: "$focus_score",
          initialValue: [],
          in: { $concatArrays: [ "$value", "$this" ] }
        }
      },
      active_score: {
        $reduce: {
          input: "$active_score",
          initialValue: [],
          in: { $concatArrays: [ "$value", "$this" ] }
        }
      }
    }
  }
])

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