聚合比较 mongodb 中的两个数组？

Question

我有以下查询结果。

[
  {
    "dayCount": 3,
    "dayRange": [
      "2021-05-27",
      "2021-05-28",
      "2021-05-29",
      "2021-05-30",
      "2021-05-31",
      "2021-06-01",
      "2021-06-02"
    ],
    "totalUserCount": 4,
    "userCountPerDay": [
      {
        "createdAt": "2021-05-28",
        "userCount": 2
      },
      {
        "createdAt": "2021-06-02",
        "userCount": 1
      },
      {
        "createdAt": "2021-06-01",
        "userCount": 1
      }
    ]
  }
]

这是按日期划分的用户访问。
我需要比较“dayRange”和“userCountPerDay.createdAt”

对于“userCountPerDay.createdAt”中不存在的日期，将“userCount”设置为 0

我想使用 mongo 聚合来跟踪结果
请帮助我。

[
  {
    "dayCount": 3,
    "totalUserCount": 4,
    "userCountPerDay": [
      {
        "createdAt": "2021-05-27",
        "userCount": 0
      },
      {
        "createdAt": "2021-05-28",
        "userCount": 2
      },
      {
        "createdAt": "2021-05-29",
        "userCount": 0
      },
      {
        "createdAt": "2021-05-30",
        "userCount": 0
      },
      {
        "createdAt": "2021-05-31",
        "userCount": 0
      },
      {
        "createdAt": "2021-06-01",
        "userCount": 1
      },
      {
        "createdAt": "2021-06-02",
        "userCount": 1
      }
    ]
  }
]

谢谢

Answer 1

$project 显示必填字段
$map 迭代 dayRange 数组
$cond 检查当前日期是否在 userCountPerDay.createdAt 数组中，
- 是，$indexOfArray 获取数组索引或 userCountPerDay 数组中的当前日期，$arrayElemAt 从 returned 索引[=31 获取 element/object =]
- 无，return createdAt 和 userCount 字段

db.collection.aggregate([
  {
    $project: {
      dayCount: 1,
      totalUserCount: 1,
      userCountPerDay: {
        $map: {
          input: "$dayRange",
          in: {
            $cond: [
              { $in: ["$$this", "$userCountPerDay.createdAt"] },
              {
                $arrayElemAt: [
                  "$userCountPerDay",
                  { $indexOfArray: ["$userCountPerDay.createdAt", "$$this"] }
                ]
              },
              {
                createdAt: "$$this",
                userCount: 0
              }
            ]
          }
        }
      }
    }
  }
])

Playground

聚合比较 mongodb 中的两个数组？

aggregate compare two array in mongodb?

arrays

compare

aggregate

mongodb