ceylon-spring-experiments

Let's smush Ceylon, Spring Boot, and Thymeleaf together and see what happens!

Run the demo::run function to fire up a server on localhost:8080 and experiment with the simple CRUD webapp. Log in as admin1 or admin2 to get elevated privileges or anybody between user1 and user5 to get normal privileges.

Fun stuff

• Look how clean demo.domain::Product is! Since Ceylon takes care of the getters for us, we can use direct field access when loading objects from the database and we're good to go.
• By annotating demo.services.impl::CrudServiceImpl.repository with formal, we enforce the contract that each class in demo.services.impl must specify which repository interface it's going to use while also being able to provide default implementations of some common tasks.
• The compiler's "EE Mode" lets us jump through fewer hoops: we don't have to annotate all our fields with default, we can use Ceylon Lists, Maps, and Sets, in many-to-many fields, etc.

Less fun stuff

• There's a definite tradeoff between having 100% immutable entity classes and making it easy to, well, mutate instances of them. We either have to write what amounts to a copy constructor for each entity class or bite the bullet and add variable annotations and give up immutability.
• "EE Mode" only works with List, Map, and Set, not {T*}, MutableSet<T>, etc.

Important configuration options

See .ceylon/config for important configuration options, notably:

• Automatically and fully exporting Maven dependencies makes sure that the dependencies brought in by the Spring Starter modules make it onto the classpath.
• Using a flat classpath lets Spring do its stuff without Ceylon's usual module management getting in its way.

Thymeleaf

You can find the Thymeleaf templates in the resource/demo/ROOT/templates/fragments directory. They use an unusual, inside-out layout pattern I like, where, instead of having to keep the page structure consistent between templates, having to remember to include the header and footer fragments, etc., templates pass themselves to the Layout fragment, which turns around and inserts the content where it needs to go. The Layout.js script handles jumping through the right hoops to keep such templates looking natural. If you're using Chrome, please see the note in that file, because you'll need a certain command-line option in order for this trick to work.

Inspirations

Thanks to the following for inspiring this experiment and providing example code that helped me figure out how this stuff fits together:

• https://springframework.guru/spring-boot-web-application-part-2-using-thymeleaf/
• https://github.com/lucono/ceylon-springboot-demo
• https://github.com/DiegoCoronel/ceylon-spring-boot

License

Public domain! Go nuts!