Read JSON file in Github Actions - json

Question

I want to read a JSON file and use a property in a string in a Github Actions YAML file. How do I do this?
(I want the version of the package.json)

Answer 1

Use the built-in fromJson(value) (see here: https://docs.github.com/en/actions/learn-github-actions/expressions#fromjson)
Reading a file depends on the shell you're using. Here's an example for sh:
name: Test linux job
on:
push
jobs:
testJob:
name: Test
runs-on: ubuntu-latest
steps:
- id: set_var
run: |
content=`cat ./path/to/package.json`
# the following lines are only required for multi line json
content="${content//'%'/'%25'}"
content="${content//$'\n'/'%0A'}"
content="${content//$'\r'/'%0D'}"
# end of optional handling for multi line json
echo "::set-output name=packageJson::$content"
- run: |
echo "${{fromJson(steps.set_var.outputs.packageJson).version}}"
Multi line JSON handling as per https://github.community/t5/GitHub-Actions/set-output-Truncates-Multiline-Strings/td-p/37870
GitHub issue about set-env / set-output multi line handling: https://github.com/actions/toolkit/issues/403

Answer 2

Below is a version of the example from Official GHA Docs that includes two changes:
Loads json from a file (./your.json)
Removes newline characters (Source)
Uses fromJson to parse the output and set a matrix variable.
name: build
on: push
jobs:
job1:
runs-on: ubuntu-latest
outputs:
matrix: ${{ steps.set-matrix.outputs.matrix }}
steps:
- id: set-matrix
run: |
JSON=$(cat ./your.json)
echo "::set-output name=matrix::${JSON//'%'/'%25'}"
job2:
needs: job1
runs-on: ubuntu-latest
strategy:
matrix: ${{fromJson(needs.job1.outputs.matrix)}}
steps:
- run: build

Answer 3

on: [push, pull_request]
name: Build
jobs:
build:
name: Example
runs-on: ubuntu-latest
steps:
- uses: actions/checkout#v2
with:
path: './'
- run: |
echo "`jq '.base_config[0].value="Alpha-21"' config.json `" > config.json
echo "`jq '.base_config[1].value="1.2.14"' config.json`" > config.json
echo "`jq '.base_config[2].value="29/12/2020"' config.json `" > config.json
- uses: EndBug/add-and-commit#v6
with:
message: 'Add the version and date'
add: '*.json --force'
cwd: './'
token: ${{ secrets.TOKEN }}

Answer 4

Use a multi line environment variable:
- run: |
echo 'PACKAGE_JSON<<EOF' >> $GITHUB_ENV
cat ./package.json >> $GITHUB_ENV
echo 'EOF' >> $GITHUB_ENV
- run: |
echo '${{ fromJson(env.PACKAGE_JSON).version }}'
This avoids any need for escaping.

Answer 5

Inspired by answer from #dastrobu which adds key/val to $GITHUB_ENV and using jq to transform/minify package.json to a single line:
- run: echo "PACKAGE_JSON=$(jq -c . < package.json)" >> $GITHUB_ENV
- run: echo '${{ fromJson(env.PACKAGE_JSON).version }}'

Answer 6

I once used this to get the value from the json data. Hope this helps
- name: fetch the json value
run: |
githubjson=`cat $GITHUB_EVENT_PATH`
echo $githubjson
number=`echo $(jq -r '.number' <<< "$githubjson")`
PRTitle=`echo $(jq -r '.pull_request.title' <<< "$githubjson")`
PRUrl=`echo $(jq -r '.pull_request.html_url' <<< "$githubjson")`
PRBody=`echo $(jq -r '.pull_request.body' <<< "$githubjson")`

Answer 7

With Powershell:
- name: Read json
id: read-json
shell: pwsh
run: |
$json = Get-Content yourfile.json | ConvertFrom-Json
echo "::set-output name=prop::$(echo $json.prop)"
- run: echo ${{ steps.read-json.outputs.prop}}

Answer 8

You can easily use the Script action for this.
- name: "Read JSON"
uses: actions/github-script#v6
id: check-env
with:
result-encoding: string
script: |
try {
const fs = require('fs')
const jsonString = fs.readFileSync('./dir/file.json')
var apps = JSON.parse(jsonString)
} catch(err) {
core.error("Error while reading or parsing the JSON")
core.setFailed(err)
}