jq_tut.sh - Simple jq tutorial by example

jq_tut.sh

#!/usr/bin/env bash

jq_tut() {
	local expr=$1 doc=$2
	shift 2
	echo "--> cat doc.json"
	echo "$doc"
	echo
	echo "--> # $comment"
	echo "    cat doc.json | jq" "$@" "'$expr'"
	jq "$@" "$expr" <<<"$doc"
}

usage() {
	echo "Usage: $0 n"
	echo
	echo " 'n' is a number of tutorial (1..9)"
	echo
	return 1
}

main() {
	local comment doc step=$1

	if [[ -z $step ]]; then
		usage >&2
		return $?
	fi

	read -r -d '' doc <<-EOF
	{
	  "value": [
	    {
	      "releaseEnvironment": {
	        "id": 1,
	        "name": "___PRD___"
	      }
	    },
	    {
	      "releaseEnvironment": {
	        "id": 2,
	        "name": "___DEV___"
	      }
	    }
	  ]
	}
	EOF

	comment='selecionando o valor da chave "value" do objeto raiz'
	[[ $step = 1 ]] && jq_tut '.value' "$doc"

	comment='selecionando o primeiro item do array do valor do passo anterior'
	[[ $step = 2 ]] && jq_tut '.value[0]' "$doc"

	comment='selecioando o "id" da chave "releaseEnvironment" do item do passo anterior'
	[[ $step = 3 ]] && jq_tut '.value[0].releaseEnvironment.id' "$doc"

	comment='filtrando os itens do "value" que o valor da chave "releaseEnvironment.id" > 1'
	[[ $step = 4 ]] && jq_tut '.value[] | select(.releaseEnvironment.id > 1)' "$doc"

	comment='filtrando os itens do "value" que o valor da chave "releaseEnvironment.name" contenha "PRD"'
	[[ $step = 5 ]] && jq_tut '.value[] | select(.releaseEnvironment.name | test("PRD"))' "$doc"

	comment='criando uma lista somente com os nomes dos releases'
	[[ $step = 6 ]] && jq_tut '.value | map(.releaseEnvironment.name)' "$doc"

	comment='echo dos nomes dos releases por linha'
	[[ $step = 7 ]] && jq_tut '.value[] | .releaseEnvironment.name' "$doc" -r

	comment='echo dos nomes dos releases por linha filtrando por "PRD"'
	[[ $step = 8 ]] && jq_tut '.value[] | .releaseEnvironment.name | select(test("PRD"))' "$doc" -r

	comment='criando uma chave "hash" combinada entre "id" e "name" em cada "releaseEnvironment"'
	[[ $step = 9 ]] && jq_tut '.value | map(.releaseEnvironment as $r | .releaseEnvironment.hash |= ($r.id | tostring) + "_" + $r.name)' "$doc"
}

main "$@"

jq is a lightweight and flexible command-line JSON processor.

./jq_tut.sh

Usage: ./jq_tut.sh n

 'n' is a number of tutorial (1..9)

./jq_tut.sh 1

--> cat doc.json
{
  "value": [
    {
      "releaseEnvironment": {
        "id": 1,
        "name": "___PRD___"
      }
    },
    {
      "releaseEnvironment": {
        "id": 2,
        "name": "___DEV___"
      }
    }
  ]
}

--> # selecionando o valor da chave "value" do objeto raiz
    cat doc.json | jq '.value'
[
  {
    "releaseEnvironment": {
      "id": 1,
      "name": "___PRD___"
    }
  },
  {
    "releaseEnvironment": {
      "id": 2,
      "name": "___DEV___"
    }
  }
]