aggregation sum elements in array in mongoDB

I have some data like that:

{id: 1, myData: [[2, 0, 0], [0, 0, 0, 3, 0, 0], [1, 0, 0, 1, 0, 0, 1, 0, 0]]}
{id: 2, myData: [[11, 0, 0], [0, 0, 0], [1, 1, 2]]}

I need to sum all numbers in each array to unique total vaule.

Desired output:

[{id:1, sumData: 8}
{id:2, sumData: 15}]

I tried to fix through group aggregation, but it is not working:

{
    $group:
        {
        _id: "$id",
        myDataSum: {
          $sum: "$myData",
        },
      },
}

How could I get the sum for all fields?

>Solution :

One option is to use $sum inside a $reduce:

db.collection.aggregate([
  {$project: {
      sumData: {$reduce: {
          input: "$myData",
          initialValue: 0,
          in: {$add: [
              "$$value",
              {$sum: "$$this"}
          ]}
      }}
  }}
])

See how it works on the playground example