Question 110066 in Json Question posted in
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Transform JSON array to object with jq

I’m trying to transform array to object by specific key. It works fine without using stream, but not possible when stream is applied.

Data:

[
  {
    "id": "1",
    "userId": "fa51531d"
    }
    ,
    {
    "id": "2",
    "userId": "a167869a"
  }
]

I tried running this command but it throws an error.

jq -n –stream ‘fromstream(1|truncate_stream(inputs)) | INDEX(.id)’ test.json > result.json

Data above should be transformed to:

{
  "1": {
    "userId": "fa51531d",
    "id": "1"
  },
  "2": {
    "userId": "a167869a",
    "id": "2"
  },
}

I want to achieve the same result as with jq 'INDEX(.id) but I need to use stream (because of big JSON file).

Tags:

3

Answers


  1. 0

    To transform your JSON Array to JSON Object maybe you can use this

    jq reduce .[] as $item ({}; .[$item.id] = $item)

    but if you want to stream the JSON, i don’t have the solutions

    cmiiw

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  2. 0

    If your stream really looks like in your question, this should do:

    jq 'INDEX(.id)' test.json

    Output:

    {
  "1": {
    "id": "1",
    "userId": "fa51531d"
  },
  "2": {
    "id": "2",
    "userId": "a167869a"
  }
}
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  3. 0

    If you are trying to recreate the whole input object, the stream-based approach is rendered pointless. That said, using this approach, there’s no need to truncate. So either replace 1 with 0:

    jq -n --stream 'fromstream(0|truncate_stream(inputs)) | INDEX(.id)'

    Or just omit it entirely (which reveals its futility):

    jq -n --stream 'fromstream(inputs) | INDEX(.id)'

    What would make more sense, is to output a stream of objects, each indexed as with INDEX. Maybe you were looking for this:

    jq -n --stream 'fromstream(1|truncate_stream(inputs)) | {(.id):.}'

    {
  "1": {
    "id": "1",
    "userId": "fa51531d"
  }
}
{
  "2": {
    "id": "2",
    "userId": "a167869a"
  }
}
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