Nested grouping of array - mongodb

Question

There are 3 master collection of category , subcategory and criteria each, i will be building framework with any possible combination of category , subcategory and criteria which will be stored as below-
framework document is added below having list of criteriaconfig as embedded object which further have single object of category , subcategory and criteria. you can refer criteriaconfig as link table that u call in mysql.
[
{
"id": "592bc3059f3ad715002b2331",
"name": "Framework1",
"description": "framework 1 for testing",
"criteriaConfigs": [
{
"id": "592bc3059f3ad715002b232f",
"category": {
"id": "591c2f5faa187956b2d0fb39",
"name": "category1",
"description": "category1",
"deleted": false,
"createdDate": 1495019359558
},
"subCategory": {
"id": "591c2f5faa187956b2d0fb83",
"name": "subCat1",
"description": "subCat1"
},
"criteria": {
"id": "591c2f5faa187956b2d0fbad",
"name": "criteria1",
"measure": "Action"
}
},
{
"id": "592bc3059f3ad715002b232e",
"category": {
"id": "591c2f5faa187956b2d0fb37",
"name": "Process",
"description": "Enagagement"
},
"subCategory": {
"id": "591c2f5faa187956b2d0fb81",
"name": "COMM / BRANDING",
"description": "COMM / BRANDING"
},
"criteria": {
"id": "591c2f5faa187956b2d0fba9",
"name": "Company representative forgets about customer on hold",
"measure": ""
}
} ]
},
{
"id": "592bc3059f3ad715002b2332",
"name": "Framework2",
"description": "framework 2 for testing",
"criteriaConfigs": [
{
"id": "592bc3059f3ad715002b232f",
"category": {
"id": "591c2f5faa187956b2d0fb39",
"name": "category1",
"description": "category1"
},
"subCategory": {
"id": "591c2f5faa187956b2d0fb83",
"name": "subCat1",
"description": "subCat1"
},
"criteria": {
"id": "591c2f5faa187956b2d0fbad",
"name": "criteria1",
"measure": "Action"
}
}
]
}
]
i need a view containing framework that will contain all list of category and inside category there will be list of added subcategory and inside subcategory will have list of criteria for single framework.
expected result -
[
{
"id": "f1",
"name": "Framework1",
"description": "framework 1 for testing",
"categories": [
{
"id": "c2",
"name": "category2",
"description": "category2",
"subCategories": [
{
"id": "sb1",
"name": "subCat1",
"description": "subCat1",
"criterias": [
{
"id": "cr1",
"name": "criteria1",
"measure": "Action"
},
{
"id": "cr2",
"name": "criteria2",
"measure": "Action"
},
{
"id": "cr3",
"name": "criteria3",
"measure": "Action"
}]
},
{
"id": "sb2",
"name": "subCat2",
"description": "subCat2",
"criterias": [
{
"id": "cr1",
"name": "criteria1",
"measure": "Action"
},
{
"id": "cr4",
"name": "criteria4",
"measure": "Action"
}]
}]
},
{
"id": "c1",
"name": "category1",
"description": "category1",
"subCategories": [
{
"id": "sb3",
"name": "subCat3",
"description": "subCat3",
"criterias": [
{
"id": "cr1",
"name": "criteria1",
"measure": "Action"
},
{
"id": "cr2",
"name": "criteria2",
"measure": "Action"
}
]},
{
"id": "sb2",
"name": "subCat2",
"description": "subCat2",
"criterias": [
{
"id": "cr1",
"name": "criteria1",
"measure": "Action"
},
{
"id": "cr4",
"name": "criteria4",
"measure": "Action"
}]
}
]
}]
},
{
"id": "f2",
"name": "Framework2",
"description": "framework 2 for testing",
"categories": [
{
"id": "c2",
"name": "category2",
"description": "category2",
"subCategories": [
{
"id": "sb4",
"name": "subCat5",
"description": "subCat5",
"criterias": [
{
"id": "cr1",
"name": "criteria1",
"measure": "Action"
},
{
"id": "cr3",
"name": "criteria3",
"measure": "Action"
}]
},
{
"id": "sb2",
"name": "subCat2",
"description": "subCat2",
"criterias": [
{
"id": "cr1",
"name": "criteria1",
"measure": "Action"
},
{
"id": "cr4",
"name": "criteria4",
"measure": "Action"
}]
}]
},
{
"id": "c1",
"name": "category1",
"description": "category1",
"subCategories": [
{
"id": "sb3",
"name": "subCat3",
"description": "subCat3",
"criterias": [
{
"id": "cr1",
"name": "criteria1",
"measure": "Action"
},
{
"id": "cr2",
"name": "criteria2",
"measure": "Action"
}
]},
{
"id": "sb2",
"name": "subCat2",
"description": "subCat2",
"criterias": [
{
"id": "cr1",
"name": "criteria1",
"measure": "Action"
},
{
"id": "cr4",
"name": "criteria4",
"measure": "Action"
}]
}
]
}]
}
]
Note - Category document doesn't have any reference to subcategory and same way subcategory doesn't have any reference to criteria object currently as they are master data and are generic , framework is created with their combination dynamically.

Answer 1

If you want to try to do all the work in the aggregation, you could group first by subcategory, then by category like:
db.collection.aggregate([
{$unwind:"$criteriaConfigs"},
{$project:{
_id:0,
category:"$criteriaConfigs.category",
subCategory:"$criteriaConfigs.subCategory",
criteria:"$criteriaConfigs.criteria"
}},
{$group:{
_id:{"category":"$category","subCategory":"$subCategory"},
criteria:{$addToSet:"$criteria"}
}},
{$group:{
_id:{"category":"$_id.category"},
subCategories:{$addToSet:{subCategory:"$_id.subCategory",
criteria:"$criteria"}}
}},
{$project:{
_id:0,category:"$_id.category",
subCategories:"$subCategories"
}}
])
Depending on how you plan to us the return data, it may be more efficient to return each unique combination:
db.collection.aggregate([
{$unwind:"$criteriaConfigs"},
{$group:{
_id:{
category:"$criteriaConfigs.category.name",
subCategory:"$criteriaConfigs.subCategory.name",
criteria:"$criteriaConfigs.criteria.name"
}
}},
{$project:{
_id:0,
category:"$_id.category",
subCategory:"$_id.subCategory",
criteria:"$_id.criteria"
}}
])
I'm not sure from your question what shape you are expecting the return data to have, so you may need to adjust for that.