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In my application, I have a section of comments and replies under some documents.
Here's how my database schema looks like
db.updates.insertOne({
"_id": "62347813d28412ffd82b551d",
"documentID": "17987e64-f848-40f3-817e-98adfd9f4ecd",
"stream": [
{
"id": "623478134c449b218b68f636",
"type": "comment",
"text": "Hey #john, we got a problem",
"authorID": "843df3dbbdfc62ba2d902326",
"taggedUsers": [
"623209d2ab26cfdbbd3fd348"
],
"replies": [
{
"id": "623478284c449b218b68f637",
"type": "reply",
"text": "Not sure, let's involve #jim here",
"authorID": "623209d2ab26cfdbbd3fd348",
"taggedUsers": [
"26cfdbbd3fd349623209d2ab"
]
}
]
}
]
})
db.users.insertMany([
{
"_id": "843df3dbbdfc62ba2d902326",
"name": "Manager"
},
{
"_id": "623209d2ab26cfdbbd3fd348",
"name": "John"
},
{
"_id": "26cfdbbd3fd349623209d2ab",
"name": "Jim"
},
])
I want to join those two collections, and replace user ids with complete user information on all levels. So the final JSON should look like this
{
"_id": "62347813d28412ffd82b551d",
"documentID": "17987e64-f848-40f3-817e-98adfd9f4ecd",
"stream": [
{
"id": "623478134c449b218b68f636",
"type": "comment",
"text": "Hey #john, we got a problem",
"author": {
"_id": "843df3dbbdfc62ba2d902326",
"name": "Manager"
},
"taggedUsers": [
{
"_id": "623209d2ab26cfdbbd3fd348",
"name": "John"
}
],
"replies": [
{
"id": "623478284c449b218b68f637",
"type": "reply",
"text": "Not sure, let's involve #jim here",
"author": {
"_id": "623209d2ab26cfdbbd3fd348",
"name": "John"
},
"taggedUsers": [
{
"_id": "26cfdbbd3fd349623209d2ab",
"name": "Jim"
}
]
}
]
}
]
}
I know how to do the $lookup on the top-level fields, including pipelines, but how can I do with the nested ones?
I have two collections in MongoDB. One is User collection and Course collections.
My Real data in the various collection regards the course
Course collection:
{
"course": {
"_id": "612f5605dc3813a3717663fe",
"cmodules": [
"612f5612dc3813068b76646c"
"612f561adc3813e7a27664f6",
],
"title": "C++ Complete Course"
}
}
Module Collection:
{
"cmodules": [
{
"_id": "612f561adc3813e7a27664f6",
"topics": [
"612f561bdc381332647664fd"
"612f5615dc3813d8a47664bb",
"612f5617dc38130e017664de"
],
"title": "Welcome to C++",
"desc": "C++ Introduction",
},
{
"_id": "612f5612dc3813068b76646c",
"topics": [
"612f5612dc3813ef8c766473"
"612f561cdc38132d73766514",
"612f561fdc3813ad1676652d"
],
"title": "Introduction to STL",
"desc": "Learn Standard template library",
}
]
}
Topic Collection:
{
"topics": [
{
"_id": "612f561bdc381332647664fd",
"units": [
"612f561bdc3813154b766503",
"612f561cdc3813feba76650b"
],
"order": 0,
"title": "Session 1",
},
{
"_id": "612f561cdc38132d73766514",
"units": [
"612f561ddc381317b176651a",
"612f561ddc38135e3a766520",
"612f561edc3813bf45766526"
],
"title": "Session 2",
},
{
"_id": "612f561fdc3813ad1676652d",
"units": [
"612f5620dc3813491b766533",
"612f5620dc3813b5f2766539",
"612f5621dc381387d976653f"
],
"title": "Session 3",
}
]
}
I am tracking all the list of units id accessed by the student in an array(learnedUnits) at the user details.
The unit list read by the student is stored in the user's collection.
"learnedUnits": [
"612f5608dc38133ee6766411",
"61322aa16c985ae927308a82",
"612f5608dc3813268a766417",
"612f5609dc38137cd776641d"
],
Course collection that has a set of modules and every module will have a set of topics and every topic will have a set of units.
Also, I am tracking all the units ID which is read by the user in the user's collections. By doing some aggregation pipeline, I arrive with the following.
[
{
"_id": "5fd5c105694d122f4837fa0f",
"learningPath": {
"historyCourses": {
"_id": "612f5605dc3813a3717663fe",
"startedAt": "2021-09-03T13:58:32.071Z",
"learnedUnits": [
"612f5608dc38133ee6766411",
"61322aa16c985ae927308a82",
"612f5608dc3813268a766417",
"612f5609dc38137cd776641d"
],
"course": {
"_id": "612f5605dc3813a3717663fe",
"cmodules": {
"_id": "612f5612dc3813068b76646c",
"topics": [
{
"_id": "612f5612dc3813ef8c766473",
"units": [
"612f5613dc381382797664ac",
"612f5614dc38139a927664b2"
],
"title": "Session 1",
},
{
"_id": "612f5615dc3813d8a47664bb",
"units": [
"612f5615dc38131ee17664c8",
"612f5616dc381317fa7664ce",
"612f5616dc38132ac37664d5"
],
"title": "Session 2",
},
{
"_id": "612f5617dc38130e017664de",
"units": [
"612f5618dc381399cf7664e4",
"612f5618dc38138e367664ea",
"612f5619dc38137fe87664f0"
],
"title": "Session 3",
}
],
"title": "Welcome to C++",
"desc": "C++ Introduction",
},
"title": "C++ Complete Course",
}
}
}
},
{
"_id": "5fd5c105694d122f4837fa0f",
"learningPath": {
"historyCourses": {
"_id": "612f5605dc3813a3717663fe",
"startedAt": "2021-09-03T13:58:32.071Z",
"learnedUnits": [
"612f5608dc38133ee6766411",
"61322aa16c985ae927308a82",
"612f5608dc3813268a766417",
"612f5609dc38137cd776641d"
],
"course": {
"_id": "612f5605dc3813a3717663fe",
"cmodules": {
"_id": "612f561adc3813e7a27664f6",
"topics": [
{
"_id": "612f561bdc381332647664fd",
"units": [
"612f561bdc3813154b766503",
"612f561cdc3813feba76650b"
],
"order": 0,
"title": "Session 1",
},
{
"_id": "612f561cdc38132d73766514",
"units": [
"612f561ddc381317b176651a",
"612f561ddc38135e3a766520",
"612f561edc3813bf45766526"
],
"title": "Session 2",
},
{
"_id": "612f561fdc3813ad1676652d",
"units": [
"612f5620dc3813491b766533",
"612f5620dc3813b5f2766539",
"612f5621dc381387d976653f"
],
"title": "Session 3",
}
],
"title": "Introduction to STL",
"desc": "Learn Standard template library",
},
"title": "C++ Complete Course",
}
}
}
}
]
I want to find how much the user learned against the course by using the learnedUnits field above. Average against the total units with the learnedUnits field.
Is there any way to find the average of completed units in the above collection?
Im using mongoose, I have the following data of user collection:
[{
"_id": "1",
"notes": [
{
"value": "A90",
"text": "math"
},
{
"value": "A80",
"text": "english"
},
{
"value": "A70",
"text": "art"
}
]
},
{
"_id": "2",
"notes": [
{
"value": "A90",
"text": "math"
},
{
"value": "A80",
"text": "english"
}
]
},
{
"_id": "3",
"notes": [
{
"value": "A80",
"text": "art"
}
]
}]
and I have as a parameters the following array: [ "A90", "A80" ]
so I want to make a query to use this array to return only the records that have all the array items in the notes (value) table.
So for the example above it will return:
[{
"_id": "1",
"notes": [
{
"value": "A90",
"text": "math"
},
{
"value": "A80",
"text": "english"
},
{
"value": "A70",
"text": "art"
}
]
},
{
"_id": "2",
"notes": [
{
"value": "A90",
"text": "math"
},
{
"value": "A80",
"text": "english"
}
]
}]
I tried the following find query:
{ "notes": { $elemMatch: { value: { $in: valuesArray } } }}
but it returns a record even if just one element in valuesArray exist.
it turned out to be quite easy:
find({ "notes.value": { $all: arrayValues } })
here are 2 possibilities for a note taking database that will have multiple notes for multiple users to keep track of
1.
[
{
"_id": "abcd",
"userInfo": {
"userID": "1",
"notes": [
{
"noteID": "1",
"text": "123"
},
{
"noteID": "2",
"text": "456"
},
{
"noteID": "3",
"text": "789"
}
]
}
},
{
"_id": "efgh",
"userInfo": {
"userID": "2",
"notes": [
{
"noteID": "1",
"text": "123"
},
{
"noteID": "2",
"text": "456"
}
]
}
}
]
And the 2nd option:
[
{
"_id": "abcd",
"userID": "1",
"noteID": "1",
"text": "123"
},
{
"_id": "efgh",
"userID": "1",
"noteID": "2",
"text": "456"
},
{
"_id": "ijkl",
"userID": "1",
"noteID": "3",
"text": "789"
},
{
"_id": "mnop",
"userID": "2",
"noteID": "1",
"text": "123"
},
{
"_id": "wxyz",
"userID": "2",
"noteID": "2",
"text": "123"
}
]
I'd expect 1 to have a much better performance when it comes to loading notes for a single user(if the user has a ton of notes). However, 2nd option is much better when modifying and adding individual notes.
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.
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.