Add a default value to a template attribute

Issue

I would like to assign a default value to a "variableX" once it is not passed any value for a Job based on a Template

Environment

CloudBees Jenkins Enterprise
CloudBees Template plugin

Resolution

In your Job Template:

On the Attributes section, add a new one:

ID: variableX
Display Name: variableX
Type: Text-Field (for this example)

Groovy Transformation

On the Transformer section

Type: Groovy Template Transformation (for this example)
Script, as follows:

<project>
<%
// Adding default value if variable is empty
if (variableX == "" || variableX == null) {
       variableX="default-value-TEMPLATE"
}
%>
<actions/>
<description/>
<keepDependencies>false</keepDependencies>
<properties>
<org.jenkinsci.plugins.gitbucket.GitBucketProjectProperty plugin="gitbucket@0.5.1">
<linkEnabled>false</linkEnabled>
</org.jenkinsci.plugins.gitbucket.GitBucketProjectProperty>
</properties>
<scm class="hudson.scm.NullSCM"/>
<canRoam>true</canRoam>
<disabled>false</disabled>
<blockBuildWhenDownstreamBuilding>false</blockBuildWhenDownstreamBuilding>
<blockBuildWhenUpstreamBuilding>false</blockBuildWhenUpstreamBuilding>
<triggers/>
<concurrentBuild>false</concurrentBuild>
<builders>
<hudson.tasks.Shell>
<command>echo This is the value of my <%=variableX%> </command>
</hudson.tasks.Shell>
</builders>
<publishers/>
<buildWrappers/>
</project>

Jelly Transformation

On the Transformer section

Type: Jelly Template Transformation (for this example)
Script, as follows:

<?xml version='1.0' encoding='UTF-8'?>
<project>
    <j:if xmlns:j="jelly:core" test="${variableX == '' || variableX == null}">
        <j:set var="variableX" value="default-value-TEMPLATE"/>
    </j:if>
    <description></description>
    <actions/>
    <keepDependencies>false</keepDependencies>
    <properties/>
    <canRoam>true</canRoam>
    <blockBuildWhenDownstreamBuilding>false</blockBuildWhenDownstreamBuilding>
    <blockBuildWhenUpstreamBuilding>false</blockBuildWhenUpstreamBuilding>
    <triggers/>
    <concurrentBuild>false</concurrentBuild>
    <builders>
    <hudson.tasks.Shell>
        <command>echo This is the value of my ${variableX} </command>
    </hudson.tasks.Shell>
    </builders>
    <publishers/>
    <buildWrappers/>
</project>

This example example has been tested on CloudBees Jenkins Enterprise 2.32.3.2-rolling with Templates plugin 4.26

This article is part of our Knowledge Base and is provided for guidance-based purposes only. The solutions or workarounds described here are not officially supported by CloudBees and may not be applicable in all environments. Use at your own discretion, and test changes in a safe environment before applying them to production systems.