How to combine nested $lookup 3 level in mongoose? - node.js

Question

I want to combine separate collections to 1 json, but I have some problems in nested $lookup.
This is my example collections.
Collection Package_subscriptions:
[
{
"_id": "1",
"package_name": "Small",
"package_desc": "AAA",
"package_price": 10
},
{
"_id": "2",
"package_name": "Medium",
"package_desc": "BBB",
"package_price": 20
}
Collection Package_modules:
{
"_id" : 1,
"subscription_id" : 1,
"billing_model_id" : 1,
"module_id" : 1,
"created_at" : ISODate("2019-06-17T07:59:43.199Z"),
}
{
"_id" : 2,
"subscription_id" : 1,
"billing_model_id" : 3,
"module_id" : 2,
"created_at" : ISODate("2019-06-17T08:00:37.464Z"),
}
{
"_id" : 3,
"subscription_id" : 2,
"billing_model_id" : 2,
"module_id" : 1,
"created_at" : ISODate("2019-06-17T08:00:56.610Z"),
}
{
"_id" : 4,
"subscription_id" : 2,
"billing_model_id" : 4,
"module_id" : 2,
"created_at" : ISODate("2019-06-17T08:01:29.667Z"),
}
Collection Modules:
{
"_id" : 1,
"module_name" : "Call",
"status" : "Active",
}
{
"_id" : 2,
"module_name" : "SMS",
"status" : "Active",
}
Collection Billing_models
{
"_id" : 1,
"unit_count" : "Menit",
"counter" : 2000,
},
{
"_id" : 2,
"unit_count" : "Menit",
"counter" : 3000,
}
{
"_id" : 3,
"unit_count" : "SMS",
"counter" : 3000,
},
{
"_id" : 4,
"unit_count" : "SMS",
"counter" : 5000,
}
This is my code to try the issue, but there's not as expected.
Package_subscription
.aggregate([
{
$lookup: {
from: "o_package_modules",
localField: "_id",
foreignField: "subscription_id",
as: "package_modules"
}
},
{
$unwind: {
path: "$package_modules",
preserveNullAndEmptyArrays: true
}
},
{
$lookup: {
from: "o_modules",
localField: "package_modules.module_id",
foreignField: "_id",
as: 'module'
}
},
{
$lookup: {
from: "o_billing_models",
localField: "package_modules.billing_model_id",
foreignField: "_id",
as: 'billing_module'
}
}
])
.exec()
.then((pricing) => {
res.json(pricing)
})
.catch((err) => {
res.send(err)
})
I expect the output is:
[
{
"_id": "1",
"package_name": "Small",
"package_desc": "AAA",
"package_price": 10,
"package_modules": [
{
"_id": 1,
"subscription_id": 1,
"billing_model": {
"_id": 1,
"unit_count": "Menit",
"counter": 2000
},
"module": {
"_id": 1,
"module_name": "Call",
"status": "Active"
},
"created_at": "2019-06-17T07:59:43.199Z",
},
{
"_id": 2,
"subscription_id": 1,
"billing_model": {
"_id": 3,
"unit_count": "SMS",
"counter": 3000
},
"module": {
"_id": 2,
"module_name": "SMS",
"status": "Active"
},
"created_at": "2019-06-17T08:00:37.464Z",
}
]
},
{
"_id": 2,
"package_name": "Medium",
"package_desc": "BBB",
"package_price": 20,
"package_modules": [
{
"_id": 3,
"subscription_id": 2,
"billing_model": {
"_id": 2,
"unit_count": "Menit",
"counter": 3000
},
"module": {
"_id": "1",
"module_name": "Call",
"status": "Active"
},
"created_at": "2019-06-17T08:01:29.667Z",
},
{
"_id": 4,
"subscription_id": 2,
"billing_model": {
"_id": 4,
"unit_count": "SMS",
"counter": 5000
},
"module": {
"_id": 2,
"module_name": "SMS",
"status": "Active"
},
"created_at": "2019-06-17T08:01:50.285Z",
}
]
}
]
But the output from my code is:
[
{
"_id": "1",
"package_name": "Small",
"package_desc": "AAA",
"package_price": 10,
"package_modules": {
"_id": 1,
"subscription_id": 1,
"billing_model_id": 1
"module_id": 1
"created_at": "2019-06-17T07:59:43.199Z",
},
},
"billing_model": [
{
"_id": 1,
"unit_count": "Menit",
"counter": 2000
},
],
"module": [
{
"_id": 1,
"module_name": "Call",
"status": "Active"
}
]
},
{
"_id": "1",
"package_name": "Small",
"package_desc": "AAA",
"package_price": 10,
"package_modules": {
"_id": 2,
"subscription_id": 2,
"billing_model_id": 3
"module_id": 2
"created_at": "2019-06-17T07:59:43.199Z",
},
},
"billing_model": [
{
"_id": 3,
"unit_count": "SMS",
"counter": 3000
},
],
"module": [
{
"_id": 2,
"module_name": "SMS",
"status": "Active"
}
]
}
..........
// And medium where is loop again
]

Answer 1

I think there are multiple issue in your code.
In your $lookup stage, you need to setup the as field as the package_modules.billing_module and package_modules.module instead of billing_module and module, and so on, so that it becomes a field of package_module object instead of a separate object itself.
you need to unwind after each $lookup stage, as $lookup returns an array instead of an object.
You need to $group at the end of the aggregation pipeline to push all the package_modules of one subscription into one array.
After resolving all the above issues,
Your aggregation pipe should look like this:
Package_subscription
.aggregate([
{
$lookup: {
from: "o_package_modules",
localField: "_id",
foreignField: "subscription_id",
as: "package_modules"
}
},
{
$unwind: {
path: "$package_modules",
preserveNullAndEmptyArrays: true
}
},
{
$lookup: {
from: "o_modules",
localField: "package_modules.module_id",
foreignField: "_id",
as: 'package_modules.module'
}
},
{
$unwind: {
path: "$package_modules.module",
preserveNullAndEmptyArrays: true
}
},
{
$lookup: {
from: "o_billing_models",
localField: "package_modules.billing_model_id",
foreignField: "_id",
as: 'package_modules.billing_module'
}
},
{
$unwind: {
path: "$package_modules.billing_module",
preserveNullAndEmptyArrays: true
}
},
{
$group: {
_id: "$_id",
package_modules : {$push : "$package_modules"},
package_name: {$first . : "$package_name"},
package_desc: {$first . : "$package_desc"},
package_price: {$first . : "$package_price"}
}
}
])
.exec()
.then((pricing) => {
res.json(pricing)
})
.catch((err) => {
res.send(err)
})
The $push in the last $group stage will combine all package_modules into one array. And i think that is what you want at the end.
I hope this works for you.

Answer 2

thank you its working for me
var order_details_data = await OrderDetails.aggregate([{
'$match': {
`order_id`: ObjectId(val._id)
}
}, {
$sort: {
date: -1
}
}, {
$addFields: {
o_price: {
$toDouble: `$o_price`
}
}
}, {
$lookup: {
from: `products`,
localField: `product_id`,
foreignField: `_id`,
as: `product_id`,
},
}, {
$unwind: {
path: `$product_id`,
preserveNullAndEmptyArrays: true
}
}, {
$lookup: {
from: `productvarientvalues`,
localField: `product_id.material_id`,
foreignField: `_id`,
as: `product_id.material_id`,
},
}, {
$unwind: {
path: `$product_id.material_id`,
preserveNullAndEmptyArrays: true
}
}, {
$group: {
_id: `$order_id`,
date: {
$first: `$date`
},
totalAmount: {
$sum: `$totalAmount`
},
orderDetails: {
$push: `$$ROOT`
},
delivery_address: {
$first: delivery_address
},
ship_address_id: {
$first: ship_address_id
},
// material_id: { $push: `$product_id.material_id` }
product_id: {
$push: `$product_id`
},
}
}, {
$project: {
// test: `$test`,
totalAmount: {
$multiply: [`$qty`, `$o_price`]
},
o_price: `$o_price`,
product_id: `$product_id`,
order_id: `$order_id`,
user_id: `$user_id`,
product_id: {
$arrayElemAt: [`$product_id`, 0]
},
data: {
$arrayElemAt: [`$data`, 0]
},
qty: `$qty`,
date: {
$dateToString: {
format: `%M `,
date: `$date`
}
},
discount: `$discount`,
examTotal: {
$sum: [`$qty`, `$price`]
},
createdAt: {
$dateToString: {
format: `%Y-%m-%d %H:%M`,
date: `$createdAt`
}
},
}
}