maven archetype: generate a default value for requiredProperty from a value of an existing property

Question

I want to set a default value for a requiredProperty in archetype-metadata.xml such that it is based on another property passed from command line. Say

<requiredProperty key="customProperty">
        <defaultValue>${artifactId.toUpperCase()}</defaultValue>
</requiredProperty>

However, when I use the resulting archetype to generate a new project, it is not the project's artifactId that gets uppercased, but rather the archetype's artifactId. Whereas when I change it to

<requiredProperty key="customProperty">
        <defaultValue>${artifactId}</defaultValue>
</requiredProperty>

I get the project's artifactId as one would expect.

Is there a way to assign a default value for a custom property based on the value of another property?

Note: this happens only in interactive mode.

How to reproduce:

mvn -B archetype:generate -DartifactId=archet -DgroupId=com.example -Dversion=1.0-SNAPSHOT -DarchetypeArtifactId=maven-archetype-archetype

For some reason, archetype.xml gets generated. It is my understanding, it is an old format. Replaced it with archetype-metadata.xml (minimized for the sake of an example):

<?xml version="1.0" encoding="UTF-8"?>
<archetype-descriptor name="basic">

    <requiredProperties>
        <requiredProperty key="customPropertyUppercased">
            <defaultValue>${artifactId.toUpperCase()}</defaultValue>
        </requiredProperty>
        <requiredProperty key="customProperty">
            <defaultValue>${artifactId}</defaultValue>
        </requiredProperty>

        <!--JUnit version to use in generated project-->
        <requiredProperty key="junit-version">
            <defaultValue>4.12</defaultValue>
        </requiredProperty>
    </requiredProperties>

    <fileSets>
        <fileSet filtered="true" packaged="true">
            <directory>src/main/java</directory>
        </fileSet>
        <fileSet filtered="true" packaged="true">
            <directory>src/test/java</directory>
        </fileSet>
    </fileSets>

</archetype-descriptor>

A template at ./src/main/resources/archetype-resources/src/main/java/App.java:

package ${groupId}.${artifactId};

/**

${customPropertyUppercased}

${customProperty}

*/
public class App
{
    public static void main( String[] args )
    {
        System.out.println( "Hello World!" );
    }
}

Generating a new project using the resulting archetype

mvn archetype:generate -DgroupId=com.example -DartifactId=stacktest -DarchetypeArtifactId=archet -DarchetypeGroupId=com.example -DarchetypeCatalog=local

with all properties set to default produces stacktest/src/main/java/com/example/App.java:

package com.example.stacktest;

/**

ARCHET

stacktest

*/
public class App
{
    public static void main( String[] args )
    {
        System.out.println( "Hello World!" );
    }
}

So, the customPropertyUppercased is based on the archetype's artifactId, while customProperty is based on the project's artifactId.

Answer 1

This is a bug in the archetype plugin, and is documented here: https://issues.apache.org/jira/browse/ARCHETYPE-490