How do i parse a text file that has json and get array element

Question

I am trying to parse a text file with json and get one of the element from jsonArray. Below is the json i am trying to parse

[
  {
    "ContainerConfig": {
      "Labels": {
        "commit-id": "abcdef123d",
        "author": "Jon"
      }
    }
  }
]

Below is my groovy implementation in jenkinsfile

def jsonStr=readFile('temp.txt').trim()
//here temp.txt consist of above json 

JsonSlurper slurper = new JsonSlurper()
def parsedJson=slurper.parseText(jsonStr)

def commitId=parsedJson[0].ContainerConfig.Labels.commit-id

I am getting this errorMsg -

java.lang.ClassCastException: org.jenkinsci.plugins.workflow.steps.EchoStep.message expects class java.lang.String but received class java.util.ArrayList 

        

Answer 1

Using the JsonSlurper is not really best practice and can cause problems with CPS, use readJSON instead (which is also easier to use IMO).

I also suspect that the - in commit-id causes the error and you should the ["commit-id"] snytax instead.