是否可以使用 MongoDB 的聚合框架使用文件夹键对通道进行分组，而无需加入文档？
[{key: 1, channels: {A: [], B: [], etc}}, {key: 2, channels: {A: [], B: [], etc}}]
我正在尝试使用$unwind然后$group按文件夹名称，但似乎不可能。
文件：
[
{
key: 1,
channels: [
{
"id": 1,
"name": "XXX",
"folder": "C"
},
{
"id": 2,
"name": "XXX",
"folder": "A"
},
{
"id": 3,
"name": "XXX",
"folder": "B"
},
{
"id": 4,
"name": "XXX",
"folder": "A"
},
{
"id": 5,
"name": "XXX",
"folder": "B"
},
{
"id": 6,
"name": "XXX",
"folder": "C"
}
]
},
{
key: 2,
channels: [
{
"id": 1,
"name": "XXX",
"folder": "D"
},
{
"id": 2,
"name": "XXX",
"folder": "B"
},
{
"id": 3,
"name": "XXX",
"folder": "A"
},
{
"id": 4,
"name": "XXX",
"folder": "C"
},
{
"id": 5,
"name": "XXX",
"folder": "A"
},
{
"id": 6,
"name": "XXX",
"folder": "D"
}
]
}
]
预期结果：
[
{
key: 1,
channels: {
A: [{
"id": 2,
"name": "XXX"
},{
"id": 4,
"name": "XXX"
}],
B: [{
"id": 3,
"name": "XXX"
}, {
"id": 5,
"name": "XXX"
}],
C: [{
"id": 1,
"name": "XXX"
},{
"id": 6,
"name": "XXX"
}]
}
},
{
"key": 2,
"channels": ...
}
]
非常感谢您提前。
$group通过key和folder，channels通过提供必填字段来构造数组$groupby onlykey并channels以 key-vlaue 格式构造数组$arrayToObject将上面构造的转换channels为对象db.collection.aggregate([
{ $match: { key: { $in: [1, 2] } } },
{ $unwind: "$channels" },
{
$group: {
_id: {
id: "$key",
folder: "$channels.folder"
},
channels: {
$push: {
id: "$channels.id",
name: "$channels.name"
}
}
}
},
{
$group: {
_id: "$_id.id",
channels: {
$push: {
k: "$_id.folder",
v: "$channels"
}
}
}
},
{ $project: { channels: { $arrayToObject: "$channels" } } }
])
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