Trying to use $cond to $sum and $subtract - mongodb

Question

My documents:
_id:"DwNMQtHYopXKK3rXt"
client_id:"ZrqKavXX8ieGpx5ae"
client_name:"luana"
companyId:"z3ern2Q7rdvviYCGv"
is_active:true
client_searchable_name:"luana"
status:"paid"
items:Object
id:912602
gross_amount:1000
type:"service"
description:"Pedicure com Zé (pacote)"
item_id:"bjmmPPjqKdWfwJqtC"
user_id:"gWjCskpHF2a3xHYy9"
user_id_commission:50
user_id_amount:0
use_package:true
quantity:1
item_costs:Array
discount_cost:Object
type:"package"
value:100
charge_from:"company_only"
entity_id:"LLRirWu5DabkRna7X"
created_at:2019-10-29T10:35:39.493+00:00
updated_at:2019-10-29T10:36:42.983+00:00
version:"2"
created_by:"2QBRDN9MACQagSkJr"
amount:0
multiple_payment_methods:Array
closed_at:2019-10-29T10:36:52.781+00:00
So i made a $project:
{
_id: 0,
closed_at: 1,
serviceId: "$items.item_id",
serviceAmount: "$items.gross_amount",
discounts:"$items.discount_cost"
}
And then $group
_id: {
month: { $month: "$closed_at" },
serviceId: "$serviceId",
discountType: "$discounts.type",
discountValue: "$discounts.value"
},
totalServiceAmount: {
$sum: "$serviceAmount"
}
}
I'm trying to make a $sum of values of the categories in my DB, actually i filtered all the data, so i have exactly what i need, like that;
_id:Object
"month":10
"serviceId":"MWBqhMyW8ataGxjBT"
"discountType":""courtesy"
"discountValue":100
"totalServiceAmount":5000
So, i have 5 types of discounts on my DB, they are: Percentage (discount in percentage), courtesy (make the service amount 0), package (make the service amount 0), gross (gross discount of value) and null if there's no discount o value.
so, if the type of discount is;
Percentage: I need to subtract the discountValue for the totalServiceAmount (discountValue will be in percentage, how i do that subtract if total serviceAmount is on gross value)
Courtesy and package: I need to transform the totalServiceAmount in 0 value.
Gross: i need to subtract the discountValue for the totalServiceAmount.
Null: just let totalServiceAmount.
I tried like that, to make some test, but i really don't know if i'm goign to the right path, the result was null for every amountWithDiscount.
{
$project: {
{
amountWithDiscount: {
$cond: {
if: {
$eq: ["$_id.discountType", "null"]
},
then: "$serviceAmount", else: {
$cond: {
if: {
$eq: ["$_id.discountType", "gross"]
},
then: {
$subtract: ["$serviceAmount", "$_id.discountValue"]
},
else: "$serviceAmount"
}
}
}
}
}
Make sense?

Answer 1

I create a collection with your grouping result:
01) Example of Documents:
[
{
"_id": "5db9ca609a17899b8ba6650d",
"month": 10,
"serviceId": "MWBqhMyW8ataGxjBT",
"discountType": "courtesy",
"discountValue": 0,
"totalServiceAmount": 5000
},
{
"_id": "5db9d0859a17899b8ba66856",
"month": 10,
"serviceId": "MWBqhMyW8ataGxjBT",
"discountType": "gross",
"discountValue": 100,
"totalServiceAmount": 5000
},
{
"_id": "5db9d0ac9a17899b8ba66863",
"month": 10,
"serviceId": "MWBqhMyW8ataGxjBT",
"discountType": "percentage",
"discountValue": 10,
"totalServiceAmount": 5000
},
{
"_id": "5db9d0d89a17899b8ba6687f",
"month": 10,
"serviceId": "MWBqhMyW8ataGxjBT",
"discountType": null,
"discountValue": 10,
"totalServiceAmount": 6000
}
]
02) Query:
db.collection.aggregate([
{
$project: {
discountType: "$discountType",
amountWithDiscount: {
$cond: {
if: {
$eq: [
"$discountType",
null
]
},
then: "$totalServiceAmount",
else: {
$cond: {
if: {
$eq: [
"$discountType",
"gross"
]
},
then: {
$subtract: [
"$totalServiceAmount",
"$discountValue"
]
},
else: {
$cond: {
if: {
$eq: [
"$discountType",
"percentage"
]
},
then: {
$multiply: [
"$totalServiceAmount",
{
$subtract: [
1,
{
$divide: [
"$discountValue",
100
]
}
]
}
]
},
else: "$totalServiceAmount"
}
}
}
}
}
}
}
}
])
A working example at https://mongoplayground.net/p/nU7vhGN-uSp.
I don't know if I fully understand your problem, but
take a look and see if it solves your problem.