Sling Context-Aware Configuration (part 4) — using inheritance

Till now this series of blog posts has only worked with configuration which has been explicitly set. But when working in hierarchical systems (like the AEM content tree) it’s often useful when you can inherit things from a parent container/concept. That means, that a specific setting on a node has effect on a complete subtree below that node instead of just the single node.

And of course Inheritance works with CA-Config as well. For easier demonstration I updated the demo content at https://github.com/joerghoh/cqdump/tree/master/ca-config-example in a way, that we can edit the configuration at 3 different locations:

• /content/ca-config/configuration.html
• /content/ca-config/en/configuration.html
• /content/ca-config/fr/configuration.html

We always use the WCM.io configuration editor I introduced in the last post.

For demo purposes I also created a new configuration “de.joerghoh.cqdump.caconfig.inheritance.InheritanceDemoConfig” (code). Be aware that the configuration editor only works when the Pojo classes for the configuration are properly annotated.

Ok, let’s get started.

Open the configuration at /contnet/ca-config/configuration.html, hit the “add” button at the top and select the “Configuration to demo the inheritance” configuration. Then change the value of the “aProperty” configuration, check the “enable property inheritance” box and press “Save”.

You have created a configuration which should be inherited down to the other levels. Specifically we should be able to see it at /content/ca-config/en/configuration.html. So let’s check it.

On a repository level only the property “sling:configPropertyInherit” has been added to /conf/ca-config/content/sling:configs/de.joerghoh.cqdump.caconfig.inheritance.InheritanceDemoConfig.

It is that simple to allow configuration inheritance. And there are many usecases where this can be useful.

If you look back, we can build this functionality also the InheritanceValueMap. But right now we only scratched the surface of the CA-Config functionality. But before we dig deeper into it, I will discuss some aspects of Sling CA-Config for production usecases.