List of objects to nested objects using aggregate - mongodb

Question

I'm having the following documents in a collection
[
{
"category":"category1",
"type":"type1",
"item":"item1",
"name":"testname",
"settings":{
"enable":"true",
"mode":"1"
},
"status":"active"
},
{
"category":"category1",
"type":"type1",
"item":"item1",
"name":"testname2",
"settings":{
"enable":"true",
"mode":"1"
},
"status":"inactive"
},
{
"category":"category1",
"type":"type1",
"item":"item2",
"name":"testname3",
"settings":{
"enable":"true",
"mode":"1"
},
"status":"active"
},
{
"category":"category2",
"type":"type2",
"item":"item3",
"name":"testname4",
"settings":{
"enable":"true",
"mode":"1"
},
"status":"active"
},
{
"category":"category3",
"type":"type4",
"item":"item5",
"name":"testname5",
"settings":{
"enable":"true",
"mode":"1"
},
"status":"active"
}
]
I want to convert this into nested objects with four level. Expecting output like below
{
"category1":{
"type1":{
"item1":{
"active":[
{
"name":"testname",
"settings":{
"enable":"true",
"mode":"1"
}
}
],
"inactive":[
{
"name":"testname2",
"settings":{
"enable":"true",
"mode":"1"
}
}
]
},
"item2":{
"active":[
{
"name":"testname3",
"settings":{
"enable":"true",
"mode":"1"
}
}
]
}
}
},
"category2":{
"type2":{
"item3":{
"active":[
{
"name":"testname4",
"settings":{
"enable":"true",
"mode":"1"
}
}
]
}
}
},
"category3":{
"type4":{
"item4":{
"active":[
{
"name":"testname5",
"settings":{
"enable":"true",
"mode":"1"
}
}
]
}
}
}
}
I'm able to convert into two levels with aggregate and replaceRoot option. Unable to convert into four levels after replacing the root. How to achieve this output using mongo aggregate>

Answer 1

I'm not sure exactly how your pipeline looks as you didn't include it, however here is how I would do it by using $arrayToObject, $group and $replaceRoot to manipulate the structure into the required format:
db.collection.aggregate([
{
$group: {
_id: {
category: "$category",
type: "$type",
item: "$item",
status: "$status"
},
data: {
$push: {
name: "$name",
settings: "$settings"
},
}
}
},
{
$group: {
_id: {
category: "$_id.category",
type: "$_id.type",
item: "$_id.item"
},
statusData: {
$push: {
data: "$data",
status: "$_id.status"
}
}
}
},
{
$replaceRoot: {
newRoot: {
"$mergeObjects": [
{
_id: "$_id"
},
{
data: {
"$arrayToObject": {
$map: {
input: "$statusData",
as: "datum",
in: {
k: "$$datum.status",
v: "$$datum.data"
}
}
}
}
}
]
}
}
},
{
$sort: {
"_id.item": 1
}
},
{
$group: {
_id: {
category: "$_id.category",
type: "$_id.type"
},
items: {
$push: {
"$arrayToObject": [
[
{
k: "$_id.item",
v: "$data"
}
]
]
}
}
}
},
{
$sort: {
"_id.type": 1
}
},
{
$replaceRoot: {
newRoot: {
"$arrayToObject": [
[
{
k: "$_id.category",
v: {
"$arrayToObject": [
[
{
k: "$_id.type",
v: {
"$mergeObjects": "$items"
}
}
]
]
}
}
]
]
}
}
}
])
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