How to sum this this JSON data values below - mongodb

Question

I am Imran, Please see the JSON data below and tell how to sum the result below:
{
"_id" : "59ae33130d83f7001112ea5e",
"user" : {
"passcode" : "****",
"operator" : "premiereservices",
"phone_num" : "8587366808",
"balance" : 1.99
},
"location_id" : "58ec4e82addba5001160fc07",
"customer_id" : "premiereservices",
"shopping_cart" : {
"item_count" : 2,
"items" : [
{
"customer_id" : "premiereservices",
"barcode" : "666",
"description" : "Test Item",
"price" : 1.99,
"taxable" : false,
"fixed_price_tax" : 0.05,
"__v" : 0
},
{
"customer_id" : "premiereservices",
"barcode" : "777",
"description" : "Test Item",
"price" : 1.99,
"taxable" : false,
"fixed_price_tax" : 0.05,
"__v" : 0
}
],
"total_due" : 4.08
},
"cart_total" : 4.08,
"Date" : "2017-09-04T23:16:03-06:00",
"__v" : 0
}
{
"_id" : "59ae38f186c7e70011a4e224",
"location_id" : "58ec522a99da86001123ec47",
"customer_id" : "premiereservices",
"user" : {
"phone_num" : "4129514766",
"balance" : 0.03
},
"cart_total" : 3.55,
"shopping_cart" : {
"items" : [
{
"barcode" : "028400020008",
"description" : "Smartfood White Cheddar Popcorn",
"price" : 1.25,
"taxable" : false,
"tax_collected" : 0
},
{
"barcode" : "012000286209",
"description" : "Pureleaf Unsweetened Tea",
"price" : 2.3,
"taxable" : false,
"tax_collected" : 0
}
]
},
"Date" : "2017-09-04T23:41:05-06:00",
"__v" : 0
}
{
"_id" : "59ae3c569ce8ec00112775d6",
"location_id" : "58ec522a99da86001123ec47",
"customer_id" : "premiereservices",
"user" : {
"phone_num" : "7192358363",
"balance" : 9.99
},
"cart_total" : 3.25,
"shopping_cart" : {
"items" : [
{
"barcode" : "10002",
"description" : "GnG Burrito Bacon/GChili/Potato",
"price" : 3.25,
"taxable" : true,
"tax_collected" : 0
}
]
},
"Date" : "2017-09-04T23:55:34-06:00",
"__v" : 0
}
Result Will be
cart_total: 10.88
price: 10.78
tax_collected: 0
Please anybody help me what will be the aggregate query functions

Answer 1

There you go:
db.collection.aggregate({
$project: { // for each document...
cart_total: 1, // ...keep the "cart_total" field
price: { $sum: "$shopping_cart.items.price" }, // ...sum up all "price" fields
tax_collected: { $sum: "$shopping_cart.items.tax_collected" } // ...sum up all "price" fields
}
}, {
$group: {
_id: null, // group all documents into the same bucket and sum up a bunch of values
cart_total: { $sum: "$cart_total" },
price: { $sum: "$price" },
tax_collected: { $sum: "$tax_collected" }
}
}, {
$project: {
_id: 0 // remove the "_id" field
}
})