writeJSON groovy writes only first value to file - groovy

Question

Below is my jenkins groovy script to read data and write as json file.
import groovy.json.JsonOutput
def arn = ""
def name = ""
def os = ""
pipeline {
agent any
stages {
stage('Hello') {
steps {
script{
def ret = sh(script: 'aws devicefarm list-devices', returnStdout: true)
def jsonObj = readJSON text: ret
def currentVersion = "13.0"
def values = currentVersion.split('\\.')
def json_str = ""
for(String item: jsonObj.devices) {
os = item.os
if(!os.contains("\\.")) {
osV = os + ".0"
} else{
osV = os
}
def osValues = osV.split('\\.')
if(values[0].toInteger() <= osValues[0].toInteger()) {
name = item.name
def data = [
name: "$name",
os: "$os",
]
json_str += JsonOutput.toJson(data)
}
}
def json_beauty = JsonOutput.prettyPrint(json_str)
writeJSON(file: 'message124.json', json: json_beauty)
}
}
}
}
}
But here, it only saves the first value. Not all the values. Could you tell me where I am wrong here

Answer 1

It's not 100% clear what you actually want to end up with, but I think you want a JSON file containing the items where OS is greater than a magic number.
It's helpful to provide enough data to duplicate the problem, and eliminate everything that isn't directly related. I think what you want is something like this:
jsonObj = [
devices: [
[ os: '3', name: 'Name 1'],
[ os: '10.2', name: 'Name 10.2'],
[ os: '7', name: 'Name 7'],
[ os: '3', name: 'Name 3'],
],
]
values = ['5']
def normalizeOs(os) {
os.contains(".") ? os : "$os.0"
}
def shouldSkip(normalizedOs) {
osValues = os.split('\\.')
values[0].toInteger() > osValues[0].toInteger()
}
selected = []
for (item: jsonObj.devices) {
os = normalizeOs(item.os)
if (shouldSkip(os)) continue
selected.push([name: item.name, os: os])
}
json = new groovy.json.JsonBuilder(selected)
println(json)
Outputs:
[{"name":"Name 7","os":"7.0"},{"name":"Name 10.2","os":"10.2"}]