MONGODB update value inside object, inside array, inside collection-CodePudding

I have this collection on Mongodb:

[
  {
    _id: new ObjectId("630954ebdfec2657ac6086e5"),
    productos: [ [Object], [Object] ],
    timestamp: 2022-08-26T23:19:07.321Z,
    __v: 0
  }
]

and i would like to know how can i sum the "cantidad" value inside "productos" array.

"productos" looks like this:

[
  {
    nombre: 'sandia',
    foto: 'https://cdn3.iconfinder.com/data/icons/fruits-52/150/icon_fruit_melancia-128.png',
    precio: 12,
    cantidad: 1,
    _id: new ObjectId("62fc0daf755a14dbac449005")
  },
  {
    nombre: 'frutillas',
    foto: 'https://cdn3.iconfinder.com/data/icons/fruits-52/150/icon_fruit_morango-128.png',
    precio: 15,
    cantidad: 1,
    _id: new ObjectId("62fc14badcaffc2a39ab7b46")
  }
]

Any help would be appreciated.

happy coding!

CodePudding user response：

You don't specify what you want the output to look like, so this just "$project"s a new field with the sum.

db.collection.aggregate([
  {
    "$project": {
      "cantidadSum": {
        "$sum": "$productos.cantidad"
      }
    }
  }
])

Example output:

[
  {
    "_id": ObjectId("630954ebdfec2657ac6086e5"),
    "cantidadSum": 2
  }
]

Try it on mongoplayground.net.

CodePudding user response：

Oh!, sorry! What i want for output would be the object with the "cantidad" (quantity in spanish) sum 1

Sorry my english!

something like this with the quantity modified:

{nombre: 'sandia',
foto: 'https://cdn3.iconfinder.com/data/icons/fruits-52/150/icon_fruit_melancia-128.png',
precio: 12,
cantidad: 2,
_id: new ObjectId("62fc0daf755a14dbac449005")}

Regards!