How to count rating on group aggregation? - node.js

Question

I was stuck on mongodb aggregation to get count of rating. i have already trying to make myself pipeline. looks above
data (products collection)
{
"status": 200,
"message": null,
"data": {
"_id": "5cc570257631a313d489ba4a",
"media": [
"httpsdssd",
"dfdfd"
],
"comment": [
"5cc57f1053273c05cc60e707",
"5cc585bf6ff7a812e0e7d9d9",
"5cc5c654bc73b408787ffadc",
"5cc5c6e3bc73b408787ffadd"
],
"store": "5cc2c9710bc5d615781fcf8a",
"meta": {
"title": "Traveling Sumbar",
"price": "150000",
"max": 5,
"duration": 6,
"description": "fdf fdnf jdnf dfnkdknfkkd",
"location": {
"province": "Sumbar",
"city": "Padang"
}
},
"option": {
"is_promo": false,
"auto_delete": null
},
"created_at": "2019-04-28T09:19:33.233Z",
"updated_at": "2019-04-28T15:29:39.921Z",
"__v": 0
}
}
comment data on (products_comment)
{
"helped": [],
"deleted_at": null,
"_id": "5cc3276e32940613506c3848",
"user": "5cc2c7fb0bc5d615781fcf86",
"rating": "4",
"body": "fdfdlfdlfkdlfkdlfkd",
"created_at": "2019-04-26T15:44:46.224Z",
"updated_at": "2019-04-28T16:00:48.400Z",
"__v": 0
},
{
"helped": [],
"deleted_at": null,
"_id": "5cc3276e32940613506c3848",
"user": "5cc2c7fb0bc5d615781fcf86",
"rating": "4",
"body": "fdfdlfdlfkdlfkdlfkd",
"created_at": "2019-04-26T15:44:46.224Z",
"updated_at": "2019-04-28T16:00:48.400Z",
"__v": 0
},
{
"helped": [],
"deleted_at": null,
"_id": "5cc3276e32940613506c3848",
"user": "5cc2c7fb0bc5d615781fcf86",
"rating": "3",
"body": "fdfdlfdlfkdlfkdlfkd",
"created_at": "2019-04-26T15:44:46.224Z",
"updated_at": "2019-04-28T16:00:48.400Z",
"__v": 0
},
I have already try make aggregation pipeline like this
{
$lookup: {
from: "stores",
localField: "store",
foreignField: "_id",
as: "store"
}
},
{
$lookup: {
from: "products_comment",
localField: "comment",
foreignField: "_id",
as: "comment"
}
},
{ $unwind: "$comment" },
{
$project: {
media: 1,
"store.type": 1,
"store.profile.address.city": 1,
"meta.title": 1,
"meta.price": 1,
"comment.rating": 1
}
}
but result unlike expectation, i want result like this
{
"_id": "5cc570257631a313d489ba4a",
"media": [
"httpsdssd",
"dfdfd"
],
"comment": {
1_rating: 0, <value of rating: count of value>
2_rating: 3,
3_rating: 5,
....,
},
"store": [
{
"type": "craft",
"profile": {
"address": {
city: "Padang
}
}
}
],
"meta": {
"title": "Traveling Sumbar",
"price": "150000"
}
}
how i do to solve my problem ?

Answer 1

Below Query will give you exactly expected Output :
var query = [
{
$lookup: {
from: "comments",
localField: "comment",
foreignField: "_id",
as: "comments"
}
},
{ $unwind: "$comments" },
{ $group : {
_id: {
_id: '$_id',
rating: '$comments.rating',
media : '$media',
meta : '$meta',
store : '$store'
},
totalRating: {$sum: 1}
}
},
{
$group : {
_id : {
_id : '$_id._id',
media : '$_id.media',
meta : '$_id.meta',
store : '$_id.store'
},
comments : {
$push : {
rating : '$_id.rating',
totalRating : '$totalRating'
}
}
}
},
{
$lookup: {
from: "stores",
localField: "store",
foreignField: "_id",
as: "store"
}
},
{
$project: {
'_id' : '$_id._id',
media : '$_id.media',
store : '$store',
meta : {
title: '$_id.meta.title',
price : '$_id.meta.price'
},
comments : { "$arrayToObject": {
"$map": {
"input": "$comments",
"as": "el",
"in": {
"k": "$$el.rating",
"v": "$$el.totalRating"
}
}
}
}
}
}
];
Output :
{
"_id" : ObjectId("5cc718715290f4ed550f5305"),
"media" : [
"httpsdssd",
"dfdfd"
],
"store" : [ ],
"meta" : {
"title" : "Traveling Sumbar",
"price" : "150000"
},
"comments" : {
"3" : 1,
"4" : 2
}
}
{
"_id" : ObjectId("5cc88d99d486568c5745e4b7"),
"media" : [
"maha",
"sagar"
],
"store" : [ ],
"meta" : {
"title" : "Sagar Sumbar",
"price" : "15000"
},
"comments" : {
"3" : 2,
"5" : 1,
"1" : 1
}
}
NOTE: Store data will be fetched from stores collection by $lookup. I don't have a model/data so, not in the output.