如何更新mongodb对象以更改纯数组中的键值数组？

Question

我在MongoDB中的每个文档中都保存了一个名为“ track”的字段。每个对象内部都有一个对象，其对象带有诸如“ 0”，“ 1”等的键。我必须用数组替换这部分。

实际情况

"track" : {
                "0" : {
                        "name" : "Crossdromo A",
                        "type" : "Motocross"
                },
                "1" : {
                        "name" : "Crossdromo B",
                        "type" : "Minicross"
                }
        }

Desiderata

"track" : [
                {
                        "name" : "Crossdromo A",
                        "type" : "Motocross"
                },
                {
                        "name" : "Crossdromo B",
                        "type" : "Minicross"
                }
        ]

关于如何更改此设置的任何建议？

Answer 1

您可以使用以下aggregation：

db.getCollection('samples').aggregate([{ //Replace 'samples' with your collection name
    $match: {} //You can change this to any query if you don't want to apply it to all documents in the collection
},
{
    $addFields: {
        track: {
            $objectToArray: '$track'  //This converts it to [{k: '0', v: { "name" : "Crossdromo A", "type" : "Motocross" }}, {k: 1,..]
        }
    }
}, {
    $addFields: {
        track: '$track.v' //This pulls the 'v' key  from the previous object.
    }
}, {
    $out: 'samples' //Replace 'samples' with your collection name   
}])