Json Question posted in
Our archive of expertly curated questions and answers provides insights and solutions to common problems related to this popular data interchange format. From parsing and manipulating JSON data to integrating it with various programming languages and web services, our archive has got you covered. Start exploring today and take your JSON skills to the next level

Add key:value pairs to JSON object in Bash

I would like to add a number of key:value pairs to an existing JSON string. The values are passed as command line arguments to my script.

So far I’ve got this

data='{"update": { "labels": [] } }'

for label in "${@}";do
   objJSON=$(printf '%sn' "{ "add": ${label} }" | jq -R . | jq -s .)
   data=$(echo ${data} | jq  --argjson jsonString "$objJSON" '.update.labels += $jsonString')
done
echo ${data} >output.txt

jq --color-output . output.txt

My output is this:

{
  "update": {
    "labels": [
      "{ add: value1 }",
      "{ add: value2 }"
    ]
  }
}

but I’m trying to get this (note the quotes surrounding add and each value):

{
  "update": {
    "labels": [
      { "add": "value1" },
      { "add": "value2" }
    ]
  }
}

I can’t see where I’m going wrong – can anyone help please?

Tags:

3

Answers


  1. 0

    Since your add key is static, I’d only pass the value of the item you want to add using the correct key as varibale.

    Then you can add it by doing .. |= { $add }
    :

    jq --arg add "labelValue" '.update.labels |= { $add }' <<< "$data"
    Login or Signup to reply.
  2. 0

    Why not do everything in a single call to jq, using --args "$@" to transfer all arguments to jq, and therein the $ARGS.positional array to reference them:

    #!/bin/bash

data='{"update": { "labels": [] } }'

jq '.update.labels += [{add: $ARGS.positional[]}]' --args "$@" <<< "$data" > output.json

    Or, if you let jq also generate the initial document, it’s really just that one call:

    #!/bin/sh

jq -n '.update.labels = [{add: $ARGS.positional[]}]' --args "$@" > output.json
    Login or Signup to reply.
  3. 0

    Make sure to escape your key/value quotes:

    for label in "$@"; do
    objJSON=$(echo "{ "add": "$label" }" | jq -c .)
###       escape here-^----^---^-------^   compact-^
    data=$(echo "$data" | jq --argjson jsonString "$objJSON" '.update.labels += [$jsonString]')
done

    Here is a Bash script that handles adding new objects to the update labels array.

    #!/usr/bin/env bash

DEFAULT_OUTPUT_FILENAME=output.txt

# Function to display help
show_help() {
    echo "Usage: $(basename "$0") [options] [label1] [label2] ... [labelN]"
    echo
    echo "This script takes key-value pair arguments and adds them to a JSON document."
    echo
    echo "Options:"
    echo "  -i, --input FILE   Input JSON file to append labels to (default: ${DEFAULT_OUTPUT_FILENAME})."
    echo "  -o, --output FILE  Output to FILE instead of ${DEFAULT_OUTPUT_FILENAME}."
    echo "  -h, --help         Display this help message."
    echo
    echo "Arguments:"
    echo "  labelN        The key-value pair to add to the JSON document."
    echo
    echo "Example:"
    echo "  $(basename "$0") "label1" "label2" "label3""
    echo "  $(basename "$0") -i existing.json -o updated.json "label1" "label2""
}

# Initialize variables
input_file=${DEFAULT_OUTPUT_FILENAME}
output_file=${DEFAULT_OUTPUT_FILENAME}

# Parse options
while [[ "$1" == -* ]]; do
    case "$1" in
        -i|--input)
            input_file="$2"
            shift 2
            ;;
        -o|--output)
            output_file="$2"
            shift 2
            ;;
        -h|--help)
            show_help
            exit 0
            ;;
        *)
            echo "Unknown option: $1"
            show_help
            exit 1
            ;;
    esac
done

# Ensure at least one label is provided
if [[ $# -eq 0 ]]; then
    echo "No labels provided. Use -h or --help for usage information."
    exit 1
fi

# Initialize JSON data
if [[ -f "$input_file" ]]; then
    data=$(cat "$input_file")
else
    data='{"update": { "labels": [] } }'
fi

# Iterate over the labels
for label in "$@"; do
    # Create JSON object from the label
    objJSON=$(echo "{ "add": "$label" }" | jq -c .)
    # Append the JSON object to the labels array
    data=$(echo "$data" | jq --argjson jsonString "$objJSON" '.update.labels += [$jsonString]')
done

# Output the final JSON to a file
echo "$data" > "$output_file"

# Pretty print the JSON
jq --color-output . "$output_file"

    Here is the usage:

    [user@host ~]$ ./json_add.sh --help
Usage: json_add.sh [options] [label1] [label2] ... [labelN]

This script takes key-value pair arguments and adds them to a JSON document.

Options:
  -i, --input FILE   Input JSON file to append labels to (default: output.txt).
  -o, --output FILE  Output to FILE instead of output.txt.
  -h, --help         Display this help message.

Arguments:
  labelN        The key-value pair to add to the JSON document.

Example:
  json_add.sh "label1" "label2" "label3"
  json_add.sh -i existing.json -o updated.json "label1" "label2"
    Login or Signup to reply.
Please signup or login to give your own answer.

Back To Top
Search