how to cumulate elements in array of objects

[quanguachong]

Input is an array of object, I want to generate an object by cumulating the array's elements.

Example Input:

{
  "containers": [
    {
          "cpu": "100m",
          "memory": "200Mi"
    },
    {
          "cpu": "25m",
          "memory": "400Mi"
    }
  ]
}

expect output:

{
    "result": {
        "cpu": 125,
        "memory": 629145600000
    }
}

[quanguachong]

I resolve this issue with following code:

result[key] := value {
    keys := { key | container := input.containers[i]; _ = container[key]}
    key := keys[_]
   # canonify_value is the function to convert string-value to number.
    values := [val | val := canonify_value(input.containers[_][key],key)]
    value := sum(values)
}

The core idea is convert input.containers to the following object:

{
  "cpu": [100, 25],
  "memory": [209715200000, 419430400000]
}

and then use build-in function sum to sum elements of array.

Is there any better resolution to resolve such problem with rego?

[anderseknert]

Hi there! Did you see the units.parse built-in function? It could probably replace the canonify_value one you're using there (or not, depending on what it does exactly).

Except for that, the approach seems reasonable to me 👍

[quanguachong]

thanks for reply.