How to get key names from JSON using jq
JsonShellUnixKeyJqJson Problem Overview
curl http://testhost.test.com:8080/application/app/version | jq '.version' | jq '.[]'
The above command outputs only the values as below:
"[email protected]"
"2323"
"test"
"02-03-2014-13:41"
"application"
How can I get the key names instead like the below:
email
versionID
context
date
versionName
Json Solutions
Solution 1 - Json
You can use:
jq 'keys' file.json
Complete example
$ cat file.json
{ "Archiver-Version" : "Plexus Archiver", "Build-Id" : "", "Build-Jdk" : "1.7.0_07", "Build-Number" : "", "Build-Tag" : "", "Built-By" : "cporter", "Created-By" : "Apache Maven", "Implementation-Title" : "northstar", "Implementation-Vendor-Id" : "com.test.testPack", "Implementation-Version" : "testBox", "Manifest-Version" : "1.0", "appname" : "testApp", "build-date" : "02-03-2014-13:41", "version" : "testBox" }
$ jq 'keys' file.json
[
"Archiver-Version",
"Build-Id",
"Build-Jdk",
"Build-Number",
"Build-Tag",
"Built-By",
"Created-By",
"Implementation-Title",
"Implementation-Vendor-Id",
"Implementation-Version",
"Manifest-Version",
"appname",
"build-date",
"version"
]
UPDATE: To create a BASH array using these keys:
Using BASH 4+:
mapfile -t arr < <(jq -r 'keys[]' ms.json)
On older BASH you can do:
arr=()
while IFS='' read -r line; do
arr+=("$line")
done < <(jq 'keys[]' ms.json)
Then print it:
printf "%s\n" ${arr[@]}
"Archiver-Version"
"Build-Id"
"Build-Jdk"
"Build-Number"
"Build-Tag"
"Built-By"
"Created-By"
"Implementation-Title"
"Implementation-Vendor-Id"
"Implementation-Version"
"Manifest-Version"
"appname"
"build-date"
"version"
Solution 2 - Json
To get the keys on a deeper node in a JSON:
echo '{"data": "1", "user": { "name": 2, "phone": 3 } }' | jq '.user | keys[]'
"name"
"phone"
Solution 3 - Json
You need to use jq 'keys[]'. For example:
echo '{"example1" : 1, "example2" : 2, "example3" : 3}' | jq 'keys[]'
Will output a line separated list:
"example1"
"example2"
"example3"
Solution 4 - Json
In combination with the above answer, you want to ask jq for raw output, so your last filter should be eg.:
cat input.json | jq -r 'keys'
From jq help:
-r output raw strings, not JSON texts;
Solution 5 - Json
To print keys on one line as csv:
echo '{"b":"2","a":"1"}' | jq -r 'keys | [ .[] | tostring ] | @csv'
Output:
"a","b"
For csv completeness ... to print values on one line as csv:
echo '{"b":"2","a":"1"}' | jq -rS . | jq -r '. | [ .[] | tostring ] | @csv'
Output:
"1","2"
Solution 6 - Json
echo '{"ab": 1, "cd": 2}' | jq -r 'keys[]' prints all keys one key per line without quotes.
ab
cd
Solution 7 - Json
If your input is an array of objects,
[ { "a01" : { "name" : "A", "user" : "B" } }, { "a02" : { "name" : "C", "user" : "D" } }]
try with:
jq '.[] | keys[]'
Solution 8 - Json
Oddly enough, the accepted answer doesn’t actually answer the Q exactly, so for reference, here is a solution that does:
$ jq -r 'keys_unsorted[]' file.json
Solution 9 - Json
Here's another way of getting a Bash array with the example JSON given by @anubhava in his answer:
arr=($(jq --raw-output 'keys_unsorted | @sh' file.json))
echo ${arr[0]} # 'Archiver-Version'
echo ${arr[1]} # 'Build-Id'
echo ${arr[2]} # 'Build-Jdk'