问题描述
在我的收藏集中,我有大量的文档,每个文档包含4种类别。
-
group
-
mainCategory
-
subCategory
-
subSubCategory
我正在寻找一种通过$group
来group
的方法,在group
内应该有mainCategory
的数组,在mainCategory
中应该有是subCategory
的数组,并且在subCategory
中应该有subSubCategory
的数组。结果应仅包含类别的值/名称。
预期结果:
const result = [
{
"group": "Teknik","mainCategory": [
{
"name": "Gaming","subCategory": [
{
"name": "Playstation","subSubCategory": [
{"name": "Games"},{"name": "Accessories"},{"name": "Console"}
]
},{
"name": "Xbox",{"name": "Console"}
]
}
]
},{
"name": "Audio","subCategory": [
{
"name": "Headphones","subSubCategory": [
{"name": "Wireless"},{"name": "Non Wireless"},]
},{
"name": "Speakers","subSubCategory": [
{"name": ""},]
}
]
},]
}
]
我认为问题在于我需要$push
父类别中的每个类别并创建新的$groups
吗?但是,当添加更多$group
时,它只是“保存”的最后一个。其他的似乎没有被“保存”。还是我做错了什么?
基于上一个示例数据和工作代码。测试数据。
https://mongoplayground.net/p/C0-L-rGPfwy
集合中的产品结构
productName :"Horizon Zero Dawn"
group:"Teknik"
mainCategory: "Gaming"
subCategory:"Playstation"
subSubCategory: "Games"
我的聚集
const categories = await Product.aggregate([
{$match: {group: 'Teknik'}},{
$group: {
_id: {
group: '$group',mainCategory: '$mainCategory',subCategory: '$subCategory',subSubCategory: '$subSubCategory',}
},},{
$group: {
_id: "$_id.group",mainCategory: {
$push:
{
name: "$_id.mainCategory",subCategory: {
name: "$_id.subCategory",subSubCategory: {
name: "$_id.subSubCategory"
}
}
}
},}
},]);
有了这个,我为每个子类别获得1个对象,但是我希望它们在同一个对象中。
"_id": "Teknik","mainCategory": [
{
"name": "Gaming","subCategory": {
"name": "Xbox","subSubCategory": {
"name": "Games"
}
}
},{
"name": "Spel & Gaming","subSubCategory": {
"name": "Accessories"
}
}
},]
解决方法
该过程是从数组的末级准备的:
- subSubCategory ()(按以下3级字段分组)
- 子类别 (按2个以下级别的字段分组,并推至高于准备好的1级)
- mainCategory (按1级以下字段分组并推至高于2级预备水平)
- 组 (计划并显示准备好的3级)
让我们一步一步看
- 您的
$match
条件
db.collection.aggregate([
{ $match: { group: "Teknik" } },
-
$group
仅包含3个主要字段,请勿添加subSubCategory
- 该小组准备
subSubCategory
阵列
{
$group: {
_id: {
group: "$group",mainCategory: "$mainCategory",subCategory: "$subCategory"
},subSubCategory: {
$push: { name: "$subSubCategory" }
}
}
},
- 在
$group
上方有重复的机会subSubCategory
,因此这将删除重复的内容,如果您不想删除,则可以跳过这一部分
{
$addFields: {
subSubCategory: { $setUnion: ["$subSubCategory",[] ] }
}
},
- 现在只有两个主要字段
$group
- 这将准备
subCategory
数组,推送我们在上一组中准备的name
和subSubCategory
数组
{
$group: {
_id: {
group: "$_id.group",mainCategory: "$_id.mainCategory"
},subCategory: {
$push: {
name: "$_id.subCategory",subSubCategory: "$subSubCategory"
}
}
}
},
-
$group
通过主要group
字段 - 这将准备
mainCategory
数组,推送我们在上一组中准备的name
和subCategory
数组
{
$group: {
_id: "$_id.group",mainCategory: {
$push: {
name: "$_id.mainCategory",subCategory: "$subCategory"
}
}
}
},
-
$project
删除_id
并显示group
和mainCategory
字段
{
$project: {
_id: 0,group: "$_id",mainCategory: 1
}
}
])