Filtering objects in jq by existence of nested array values

Question

Given a document like this:

[
  {
    "KVs" : [
      {
        "Key": "animal",
        "Value": "lion"
      },
      {
        "Key": "mascot",
        "Value": "lion"
      }
    ],
    "name": "roger"
  },
  {
    "KVs" : [
      {
        "Key": "animal",
        "Value": "zebra"
      },
      {
        "Key": "mascot",
        "Value": "lion"
      }
    ],
    "name": "linda"
  }
]

I want to use jq to select only those elements of the top array that contain the KV pair animal == "lion".

The output for the above JSON document should be:

{
  "KVs" : [
    {
      "Key": "animal",
      "Value": "lion"
    },
    {
      "Key": "mascot",
      "Value": "lion"
    }
  ],
  "name": "roger"
}

Can't figure out how to accomplish this with select(). I know how to use it to select based on one specific field. e.g. by key name: .[] | select(.KVs[].Key == "animal"), right? But how do I tell it to match the same KV object on two fields (Key & Value)?

E-man · Accepted Answer · 2020-08-14 00:59:40Z

14

NM, solved it with the help of jqplay and some trial and error.

This is the solution: .[] | select(.KVs[] | .Key == "animal" and .Value == "lion")

(jqplay permalink)

edited Aug 14, 2020 at 0:59

E-man

4513 silver badges12 bronze badges

answered Dec 19, 2017 at 13:02

Assaf Lavie

76.7k37 gold badges152 silver badges207 bronze badges

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4 Comments

Michał Politowski Over a year ago

It doesn't matter here, since only one inner object matches, but in general you might prefer to use any. Compare .[]|select(.KVs|any(.Value=="lion")) and .[]|select(.KVs[]|.Value=="lion")

Assaf Lavie Over a year ago

Interesting. But what is the difference, actually? Why would I prefer to use any?

Michał Politowski Over a year ago

Compare the number of results in both cases.

user2585501 Over a year ago

Note to return the value of the name element from the result (ie "roger"), use .[] | select(.KVs[] | .Key == "animal" and .Value == "lion") | .name

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