[JENKINS-43720] NodeLabel parameters are null objects in pipeline script params

Accessing the parameter with param will give you a null object, but accessing it through env and global will give you the string of one node.

Example:

properties ([

    parameters([

[

     $class: 'BooleanParameterDefinition',

     defaultValue: false,

     description: 'This will do a clean and build of the project.',

     name: 'Rebuild'

],

[

     $class: 'NodeParameterDefinition',

     allowedSlaves: ['ALL (no restriction)'],

     defaultSlaves: ['master'],

     description: 'What nodes to run the build on.',

     name: 'NODE_PARAM',

     nodeEligibility: [$class: 'AllNodeEligibility'],

     triggerIfResult: 'allowMultiSelectionForConcurrentBuilds'

]

    ])

])


echo "NODE_PARAM: " + NODE_PARAM.getClass().toString()

echo "env.NODE_PARAM: " + env.NODE_PARAM.getClass().toString()

echo "params.NODE_PARAM: " + params.NODE_PARAM.getClass().toString()

Will give you this output:

[Pipeline] echo

NODE_PARAM: class java.lang.String

[Pipeline] echo

env.NODE_PARAM: class java.lang.String

[Pipeline] echo

params.NODE_PARAM: class org.codehaus.groovy.runtime.NullObject

As you can see, only params.NODE_PARAM is null. 

The problem is that I can not use env.NODE_PARAM or NODE_PARAM to get multiple selection of nodes, as those are only a string representation of a single node.

 

---
Originally reported by snellingen, imported from: NodeLabel parameters are null objects in pipeline script params

• status: Open
  
• priority: Minor
  
• component(s): nodelabelparameter-plugin
  
• label(s): jenkins, pipeline, plugin
  
• resolution: Unresolved
  
• votes: 13
  
• watchers: 15
  
• imported: 20251210-235911
  

Raw content of original issue

Accessing the parameter with param will give you a null object, but accessing it through env and global will give you the string of one node.


Example:



properties ([

    parameters([

        [

             $class: 'BooleanParameterDefinition',

             defaultValue: false,

             description: 'This will do a clean and build of the project.',

             name: 'Rebuild'

        ],

        [

             $class: 'NodeParameterDefinition',

             allowedSlaves: ['ALL (no restriction)'],

             defaultSlaves: ['master'],

             description: 'What nodes to run the build on.',

             name: 'NODE_PARAM',

             nodeEligibility: [$class: 'AllNodeEligibility'],

             triggerIfResult: 'allowMultiSelectionForConcurrentBuilds'

        ]

    ])

])


echo "NODE_PARAM: " + NODE_PARAM.getClass().toString()

echo "env.NODE_PARAM: " + env.NODE_PARAM.getClass().toString()

echo "params.NODE_PARAM: " + params.NODE_PARAM.getClass().toString()





Will give you this output:



[Pipeline] echo

NODE_PARAM: class java.lang.String

[Pipeline] echo

env.NODE_PARAM: class java.lang.String

[Pipeline] echo

params.NODE_PARAM: class org.codehaus.groovy.runtime.NullObject





As you can see, only params.NODE_PARAM is null. 


The problem is that I can not use env.NODE_PARAM or NODE_PARAM to get multiple selection of nodes, as those are only a string representation of a single node.


 

environment

```
Jenkins ver. 2.15 on Windows,

NodeLabel 1.7.2,

Pipeline: Groovy 2.29
```

Start with the nodelabelparameter-plugin's NodeParameterDefinition and its Pipeline: Groovy parameter handling, using the reported params.NODE_PARAM, env.NODE_PARAM, and NODE_PARAM behavior as the reproduction. Trace how multiple selected nodes are represented and verify that params exposes the selection rather than a null object while preserving existing single-node behavior.

Written by the indexing model from the issue text.