如何使用聚合展平数组数组

Question

我正在尝试使用 MongoDB(3.6) 的聚合框架来展平以下数据：

array = [
  [1899.99, 241.92, 869.99, 696],
  [2301.45, 100],
  [1468.12, 85.9],
  [14.1],
  [268.59, 27.6, 428.51, 173.85],
  [627.29, 241.92, 413.47, 229.74],
  [1687.58, 100],
  [241.11]
]

而我需要的是：

result = [1899.99, 241.92, 869.99, 696, 2301.45, 100, 1468.12, 85.9, 14.1, 268.59, 27.6, 428.51, 173.85, 627.29, 241.92, 413.47, 229.74, 1687.58, 100, 241.11]

我正在使用这个查询：

db.collection.aggregate([
  {
    $match: { code: '11122233344' }
  },
  {
    $project: {
      vencimentos: '$response.operations.expirations.value'
    }
  },
  {
    $unwind: '$vencimentos'
  },
  {
    $group: {
      _id: 'vencimentos',
      vencimentos: { $addToSet: '$vencimentos' }
    }
  },
])

这是查询的结果：

{
  "_id" : "vencimentos",
  "vencimentos" : [
    [1899.99, 241.92, 869.99, 696.11],
    [2301.45, 100],
    [1468.12, 85.9],
    [14.1],
    [268.59, 27.6, 428.51, 173.85],
    [627.29, 241.92, 413.47, 229.74],
    [1687.58, 100],
    [241.11]
  ]
}

谁能帮帮我？谢谢

Answer 1

考虑到您当前聚合的结果，您必须添加以下步骤以获得您需要的结果：

{
    $addFields: {
      vencimentos: {
        "$reduce": {
          "input": "$vencimentos",
          "initialValue": [],
          "in": {
            "$concatArrays": [
              "$$this",
              "$$value"
            ]
          }
        }
      }
    }
  }

You can test the result here

如何使用聚合展平数组数组

How flatten an array of arrays using aggregate

flatten

mongodb

aggregation-framework