Create JSON strings from Groovy variables in Jenkins Pipeline

Question

I have to create this JSON file in Groovy. I have try many things (JsonOutput.toJson() / JsonSlurper.parseText()) unsuccessfully.

{    "attachments":[       {          "fallback":"New open task [Urgent]: <http://url_to_task|Test out Slack message attachments>",          "pretext":"New open task [Urgent]: <http://url_to_task|Test out Slack message attachments>",          "color":"#D00000",          "fields":[             {                "title":"Notes",                "value":"This is much easier than I thought it would be.",                "short":false             }          ]       }    ] } 

This is for posting a Jenkins build message to Slack.

Answer 1

JSON is a format that uses human-readable text to transmit data objects consisting of attribute–value pairs and array data types. So, in general json is a formatted text.

In groovy json object is just a sequence of maps/arrays.

parsing json using JsonSlurperClassic

//use JsonSlurperClassic because it produces HashMap that could be serialized by pipeline import groovy.json.JsonSlurperClassic  node{     def json = readFile(file:'message2.json')     def data = new JsonSlurperClassic().parseText(json)     echo "color: ${data.attachments[0].color}" } 

parsing json using pipeline

node{     def data = readJSON file:'message2.json'     echo "color: ${data.attachments[0].color}" } 

building json from code and write it to file

import groovy.json.JsonOutput node{     //to create json declare a sequence of maps/arrays in groovy     //here is the data according to your sample     def data = [         attachments:[             [                 fallback: "New open task [Urgent]: <http://url_to_task|Test out Slack message attachments>",                 pretext : "New open task [Urgent]: <http://url_to_task|Test out Slack message attachments>",                 color   : "#D00000",                 fields  :[                     [                         title: "Notes",                         value: "This is much easier than I thought it would be.",                         short: false                     ]                 ]             ]         ]     ]     //two alternatives to write      //native pipeline step:     writeJSON(file: 'message1.json', json: data)      //but if writeJSON not supported by your version:     //convert maps/arrays to json formatted string     def json = JsonOutput.toJson(data)     //if you need pretty print (multiline) json     json = JsonOutput.prettyPrint(json)      //put string into the file:     writeFile(file:'message2.json', text: json)  } 

Answer 2

Found this question while I was trying to do something (I believed) should be simple to do, but wasn't addressed by the other answer. If you already have the JSON loaded as a string inside a variable, how do you convert it to a native object? Obviously you could do new JsonSlurperClassic().parseText(json) as the other answer suggests, but there is a native way in Jenkins to do this:

node () {   def myJson = '{"version":"1.0.0"}';   def myObject = readJSON text: myJson;   echo myObject.version; } 

Hope this helps someone.

Edit: As explained in the comments "native" isn't quite accurate.