How can I determine if a variable exists from within the Groovy code running in the Scripting Engine?

Question

The variable was put by ScriptEngine's put method

Aliaksandr Pyrkh · Answer 1 · 2022-09-11T17:13:54.267

42

In a groovy.lang.Script there is a method public Binding getBinding(). And groovy.lang.Binding has method public boolean hasVariable(String name).

Thus you can simply check variable existence like:

if (binding.hasVariable('superVariable')) {
// your code here
}

edited Sep 11 '22 at 17:13

answered Sep 14 '17 at 05:46

Aliaksandr Pyrkh

581
6
8

score 8 · Answer 2 · answered May 25 '19 at 16:23

8

// Example usage: defaultIfInexistent({myVar}, "default")
def defaultIfInexistent(varNameExpr, defaultValue) {
    try {
        varNameExpr()
    } catch (exc) {
        defaultValue
    }
}

answered May 25 '19 at 16:23

Maximilian Mordig

1,333
1
12
16

1

This method is better because it works around the Jenkins security sandbox. – ablarg Jan 13 '20 at 18:11
What does `varNameExpr()` do? – not2savvy Oct 05 '22 at 13:59
Better than what? The binding.hasVariable function works and seems much cleaner – ajpieri Jul 31 '23 at 12:47

score 6 · Answer 3 · answered Feb 28 '17 at 17:31

6

Variables injected by the Scripting Engine are held within binding.variables, so you can e.g. check for variable named xx:

if (binding.variables["xx"]) ...

answered Feb 28 '17 at 17:31

Valdi_Bo

30,023
4
23
41

In my context (Jenkins) I got the error : org.jenkinsci.plugins.scriptsecurity.sandbox.RejectedAccessException: Scripts not permitted to use method groovy.lang.Binding getVariables. The other answer didn't work either, but it wasn't a security problem. – andrew lorien Nov 14 '18 at 02:56
1

This is rather a Jenkins issue. Maybe you should ask a new question and mark it with *Jenkins* tag. – Valdi_Bo Nov 14 '18 at 08:40
2

@andrewlorien If you had catched such an error, you can go to Jenkins settings, "In-process Script Approval" and approve this script. – Michael A. Jan 01 '19 at 14:41

Sumeet Patil · Accepted Answer · 2023-02-02T06:36:18.273

1

Improvement for the existing solution given here https://stackoverflow.com/a/56306660/3158217 -

def defaultIfInexistent(varName, defaultValue){
    try{
        varName.toString()
        return varName
    }catch(ex){
        return defaultValue
    }
}

edited Feb 02 '23 at 06:36

answered Feb 01 '23 at 15:29

Sumeet Patil

422
3
14

How can I determine if a variable exists from within the Groovy code running in the Scripting Engine?

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