MongoDB展开多个数组

发布于09月08日

我有以下文件:

{
  "dates": [
    1399518702000,
    1399126333000,
    1399209192000,
    1399027545000
  ],
  "dress_number": "4",
  "name": "J. Evans",
  "numbers": [
    "5982",
    "5983",
    "5984",
    "5985"
  ]
}

是否可以从多个数组中展开数据，并仅从数组中获取成对的元素:

{
    "dates": "1399518702000",
    "numbers": "5982"
},
{
    "dates": "1399126333000",
    "numbers": "5983"
},
{
    "dates": "1399209192000",
    "numbers": "5984"
},
{
    "dates": "1399027545000",
    "numbers": "5985"
}

推荐答案

从3.2版开始，两个数组上都有$unwind个索引，$cmp个索引，只有$match个相等的索引.

如果您只有示例文档，此解决方案将填充您编写的内容.如果你有更多的文档，我不知道你希望在输出中得到什么，但是可以通过按文档的_id分组来解决.

db.test.aggregate([
    {
        $unwind: {
            path: '$dates',
            includeArrayIndex: 'dates_index',
        }
    },
    {
        $unwind: {
            path: '$numbers',
            includeArrayIndex: 'numbers_index',
        }
    },
    {
        $project: {
            dates: 1,
            numbers: 1,
            compare: {
                $cmp: ['$dates_index', '$numbers_index']
            }
        }
    },
    {
        $match: {
            compare: 0
        }
    },
    {
        $project: {
            _id: 0,
            dates: 1,
            numbers: 1
        }
    }
])