Spring boot 3 reactive with Kotlin coroutines and r2dbc

About

• This project is just a demo or a starting template to work with Spring boot 3 with Kotlin coroutines and r2dbc and DatabaseClient (https://docs.spring.io/spring-framework/reference/data-access/r2dbc.html)
• The project is set up to work with the H2 in-memory but you can comment the h2 config and uncomment the mysql config in the application.yml file if you prefer to work with mysql (you can clone this project to create a dockerized db: https://github.com/danygiguere/docker_db)
• If you are using IntelliJ Ultimate, you can run the requests.http file (in the test folder) to test all the available routes
• In this demo I haven't used an orm. If you'd like to user and ORM, have a look at CoroutineCrudRepository. It' is a non-blocking reactive interface for generic CRUD operations using Kotlin Coroutines.
• The app demonstrates:
  • how to create controllers, dtos, entities, and repositories with Kotlin coroutines
  • how to set up Flyway to manage migrations (it works with mysql but I wasn't able to make it work with h2)
  • how to set an exception handler to manage failed validations in a reactive context
  • how to return translated validation error messages (check the requests.http file for more info)
  • how to create custom validators
  • how to do a oneToMany relationship query
  • how to do a belongsTo relationship query
  • how to do a hasManyThrough relationship query
  • how to run suspend functions in parallel with async/await
  • how to create unit tests in a reactive context
  • how to do webclient calls with Kotlin Coroutines
  • how to data factories to seed the db and to create dtos in tests
  • how to set up Docker (I figured it out on the Docker branch (https://github.com/danygiguere/spring-boot-3-reactive-with-kotlin-coroutines/tree/Docker) but the H2DatabaseConfiguration script is problematic)
• I recommend you watch this nice video regarding coroutines and the different strategies available: https://www.youtube.com/watch?v=ahTXElHrV0c

TLDR

• Clone the project, run it (it's set up by default with H2), then go to /test/requests.http and run the requests one by one.

Todo

• add validation to block users from updating a post that doesn't belong to them
• setLocal early in the request lifecycle so that I can get it anytime with getLocale (it's already setin by default for the validations)