How to share Domain Codebase between Grails 2 and Grails 3

Question

At the moment, we have multiple grails applications built on grails 2.5.0

Our Model is in a grails plugin (2.5.0), published to a local maven repository. So far everything works great.

Now we want to create a new application with Grails 3, which relies on some of the basic Domains located in a grails2 plugin (User, Group, etc).

What would be the best way, to share those ? I dont want to maintain two code-bases for our model, one for v2 and one for v3 ...

The only thing which came into my mind is, building everything in plain groovy Classes / Interfaces, and then extending / implementing the Model in both grails2 and grails3 plugins

• core-model (contains Interfaces, abstract classes)
• grails-model-v2
• grails-model-v3

Answer 1

You're on the right track. The domain classes will probably work unchanged, but the problem is the grails plugin projects are incompatible. So you can use a plain groovy project to house your domains and then have each plugin depend on the domain project. The tricky part is telling grails that those plain groovy classes are domains. In grails 3 you can probably just apply the groovy traits that grails automatic applies to domains using doWithSpring(). I think grails 2 uses metaClass to accomplish the same thing, so the approach might be similar.