JSON – How to Grep and Print Value of a Key Stored in a Variable

jqjson

I have a variable with nested json,

a={
  "version": "3.0",
  "user": "unknown_unknown",
  "dateGenerated": "2020-07-08T11:53:23Z",
  "status": "OK",
  "data": [
    {
      "parameter": "t_2m:C",
      "coordinates": [
        {
          "lat": 39.23054,
          "lon": 9.11917,
          "dates": [
            {
              "date": "2020-07-08T15:53:23Z",
              "value": 25.1
            }
          ]
        }
      ]
    }
  ]
}

Looking for a way to grep the "value" in the nested json (like the one highlighted) in variable a.

I'am using grep and jq but I can't show value, it shows "dates"
(echo $result | grep -Po '"dates":.*?[^\\],.*?[^\\]"')
but not just the value.

Any help?

Best Answer

You want the "value" from (the first object in the "dates" array) from (the first object in the "coordinates" array) from (the first object in the "data" array)

$ a='{"version":"3.0","user":"unknown_unknown","dateGenerated":"2020-07-08T11:53:23Z","status":"OK","data":[{"parameter":"t_2m:C","coordinates":[{"lat":39.23054,"lon":9.11917,"dates":[{"date":"2020-07-08T15:53:23Z","value":25.1}]}]}]}'
$ echo "$a" | jq -r '.data[0].coordinates[0].dates[0].value'
25.1

Related Solutions

Jq print key and value for all in sub-object

Simply pipe to keys function:

Sample input.json:

{
    "connections": {
        "host1": { "ip": "10.1.2.3" },
        "host2": { "ip": "10.1.2.2" },
        "host3": { "ip": "10.1.18.1" }
    }
}

jq -r '.connections | keys[] as $k | "\($k), \(.[$k] | .ip)"' input.json

The output:

host1, 10.1.2.3
host2, 10.1.2.2
host3, 10.1.18.1

JSON – How to Print Path and Key Values

I'm not super knowledgeable on jq but I found this on the interwebs and I think it will work in your case:

Cut and paste version:

jq -r 'paths(scalars) as $p  | [ ( [ $p[] | tostring ] | join(".") ), ( getpath($p) | tojson )] | join(": ")' short.json

Easy(er) to read version:

jq -r '
paths(scalars) as $p
  | [ ( [ $p[] | tostring ] | join(".") )
    , ( getpath($p) | tojson )
    ]
  | join(": ")
' short.json

Result:

Reservations.0.Instances.0.ImageId: "ami-a"
Reservations.0.Instances.0.InstanceId: "i-a"
Reservations.0.Instances.0.InstanceType: "t2.micro"
Reservations.0.Instances.0.KeyName: "ubuntu"

And because I want the bonus points, here's a hacky sed you can tack on to get the output you want:

... | sed "s/^/\'./; s/:/\':/; s/\.0/[]/g"

Which outputs:

'.Reservations[].Instances[].ImageId': "ami-a"
'.Reservations[].Instances[].InstanceId': "i-a"
'.Reservations[].Instances[].InstanceType': "t2.micro"
'.Reservations[].Instances[].KeyName': "ubuntu"

Best Answer

Related Solutions

Jq print key and value for all in sub-object

JSON – How to Print Path and Key Values

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