MongoDB : aggregate value from two arrays in document (mapping)

Question

Am new to MongoDB and I have two arrays in a document like this. I want to get a specific value from both arrays. For example "received_bytes" and its value from the values array "43118304". I did some research but I think am lost.

fields:{
 "time",
 "received_bytes",
 "sent_bytes"
}
values:{
 "2021-11-22T08:08:30Z",
 43118304,
 43105744
}

Basic aggregate I have done

return await Metric.aggregate([
  {
    $match: matches,
  },
  { $sort: { _id: 1 } },
  {
    $group: {
      _id: params.field, // received_bytes
      values: { $push: '$values' }, // array of values for received_bytes
    },
  },
]);

What i expect:

{
  _id:"received_bytes",
  values:[] //all received_bytes values
}

Thanks for help.

if you can give valid JSON data and the expected output

Takis
– Takis

2021-11-23 18:55:21 +00:00
Commented Nov 23, 2021 at 18:55 — Takis
– Takis, Commented Nov 23, 2021 at 18:55
@Takis_ Its already real json data.

Nasouh
– Nasouh

2021-11-24 11:58:03 +00:00
Commented Nov 24, 2021 at 11:58 — Nasouh
– Nasouh, Commented Nov 24, 2021 at 11:58

Nasouh · Accepted Answer · 2021-11-23 11:38:55Z

1

I didn't find best answer so I grouped the results then loop on them to get my values

 const metrics = await Metric.aggregate([
  {
    $match: matches,
  },
  { $sort: { _id: 1 } },
  // mapping fields=>values where field equal to params.field
  {
    $group: {
      _id: '$fields',
      values: { $push: '$values' },
    },
  },
]);

answered Nov 23, 2021 at 11:38

Nasouh

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