Mongodb - Aggregation and Sum for each object - mongodb

Question

I need to aggregate for each "Product" object from the sales database, and sum "Price" and "Quantity" to make a product classification.
I was able to group by "Products" but I can't sum Price and Quantity to the each object.
{$group: {
_id: '$products.items',
totalprice:{$sum: "$products.items.price"},
}}
Below sample of sales database, where I need to return the sum of the "Price" and "Quantity" fields sold for each "Products".
{
"_id": {
"$oid": "5d753707c0cd851e80da914c"
},
"created_on": {
"$date": {
"$numberLong": "1567962886000"
}
},
"custumer": {
"name": "Teste",
"cep": "teste",
"address": "teste",
"district": "test",
"city": "test",
"numb": "50",
"comple": "test",
"state": "test",
"cpf": "test",
"birth": "30/09/1977",
"email": "test#gmail.com",
"phone": {
"$numberDouble": "1111111111111"
},
"gender": "M",
"portalt": {
"status": "true",
"vendor": "test",
"phone": {
"$numberDouble": "11111111111"
},
"sim": "011111111111",
"salesnumb": "1222222222222222222"
}
},
"payment": {
"method": "Boleto",
"type": "Parcelado",
"installments": "5",
"billing_date": "15"
},
**"products": {
"items": {
"5d515979736802000415a561": {
"item": {
"_id": "5d515979736802000415a561",
"name_produto": "Product 1",
"resumo": "Minutos ilimitados,20GB + 2GB",
"price": "110",
"_image": "images/test.jpg"
},
"quantity": {
"$numberInt": "2"
},
"price": {
"$numberInt": "220"
}
},
"5d515aba736802000415a562": {
"item": {
"_id": "5d515aba736802000415a562",
"name_produto": "Product 2",
"resumo": "Minutos ilimitados,3GB + 1GB",
"price": "80",
"_image": "images/test.jpg"
},
"quantity": {
"$numberInt": "1"
},
"price": {
"$numberInt": "80"
}
},
"5d515dbf736802000415a564": {
"item": {
"_id": "5d515dbf736802000415a564",
"name_produto": "Product 3",
"resumo": "Minutos ilimitados,30GB + 3GB",
"price": "150",
"_image": "images/test.jpg"
},
"quantity": {
"$numberInt": "1"
},
"price": {
"$numberInt": "150"
}
}
},**
"totalItems": {
"$numberInt": "4"
},
"totalPrice": {
"$numberInt": "450"
}
},
"seller": {
"_id": {
"$oid": "5cd086787dc59921bcad94d8"
},
"name": "test"
}
}
I need output something like:
_id:Object
5d515979736802000415a561:{sum_price: 300, sum_quantity: 30 }
5d515aba736802000415a562:{sum_price: 500, sum_quantity: 60 }
5d515dbf736802000415a564:{sum_price: 600, sum_quantity: 70 }
Thanks so much!

Answer 1

So let's go with the OP ask to sum the individual product price and quantity. Stripping away the other fields which are not relevant to the ask, we arrive at something like this:
var r =
[
{
_id:0,
"products": {
"items": {
"5d515979736802000415a561": {
"quantity": 2,
"price": 220,
},
"5d515aba736802000415a562": {
"quantity": 1,
"price": 80
}
}
}
}
, {
_id:1,
"products": {
"items": {
"5d515979736802000415a561": { // deliberately same id as doc above but different quantity and price
"quantity": 3,
"price": 330
},
"5d515aba736802000415a562": { // same
"quantity": 2,
"price": 160
},
"5d515979736802000415ZZZZ": { // different than above; adds "third item"
"quantity": 4,
"price": 200
}
}
}
}
];
Note that the whole inner item field is basically not important, not the least of which it only contains the unit price, not the total price (amount) and quantity per product.
"5d515dbf736802000415a564": {
"item": {
"_id": "5d515dbf736802000415a564",
// etc
So now we employ the $objectToArray to turn the keys into rvals. That gives us something we can $group on, and so here is a solution:
db.foo.aggregate([
{$project: {X: {$objectToArray: "$products.items"}}}
,{$unwind: "$X"}
,{$group: {_id: "$X.k", tot_q: {$sum:"$X.v.quantity"}, tot_amt: {$sum:"$X.v.price"}} }
]);
which given the input above yields:
{ "_id" : "5d515979736802000415ZZZZ", "tot_q" : 4, "tot_amt" : 200 }
{ "_id" : "5d515aba736802000415a562", "tot_q" : 3, "tot_amt" : 240 }
{ "_id" : "5d515979736802000415a561", "tot_q" : 5, "tot_amt" : 550 }