How to properly parse JSON in Groovy

Question

I am not sure how to properly parse through nested JSON using Groovy. I have included a working Python script so you can see exactly what I'm trying to do in Groovy.

JSON I need to parse:

json_payload = {"number": 3585, "url": "https://jenkins.test.com/job/test/3585/",
                  "displayName": "test_3585", "timestamp": 1516992464686,
                  "actions": [{"causes": [{"userId": "test"}]}]}

What I want to do (Python):

class JenkinsParser:
    def __init__(self, json_data):

        self.display_name = json_data['displayName']
        self.url = json_data['url']
        self.start_time = json_data['timestamp']
        self.exec_url = json_data['url']
        self.exec_number = json_data['number']
        self.user = None
        actions = json_data['actions']
        for a in actions:
            if 'causes' in a:
                for cause in a['causes']:
                    if 'userId' in cause:
                        self.user = cause['userId']

        url_split = self.execution_url.split("/job/")
        self.jenkins_url = url_split[0]
        self.job_name = url_split[-1].split("/")[0]

Note: The Groovy does not necessarily need to be a class, and doesn't need to use JSonSlurper

If I use JsonSlurper

def slurper = new groovy.json.JsonSlurper()
def result = slurper.parseText(json_payload)

Can I access all the values I need like so?

result.displayName
result.url
result.timestamp
result.url
result.number
result.actions.causes.userId

I'm not sure how to grab userId..

Answer 1

Yes, you can access the values like you described.

You could access userId like result?.actions.first().causes.first().userId? if you're sure your data is structured exactly like that. If you may or may not have actions, or may or may not have causes, you could do something like result?.actions?.first()?.causes?.first()?.userId? to make your access null-safe, or you could use the spread (*.) operator to access userId if there may be multiple actions or causes.

Per your comment about something returning null, this works as expected:

def json_payload = """{"number": 3585, "url": "https://jenkins.test.com/job/test/3585/", "displayName": "test_3585", "timestamp": 1516992464686, "actions": [{"causes": [{"userId": "test"}]}]}"""
def slurper = new groovy.json.JsonSlurper()
def result = slurper.parseText(json_payload)
return result?.actions?.first()?.causes?.first()?.userId?

and returns "test". If you are not seeing similar results you may have a syntax error or different key in your actual data.