Javalin was upgraded to version 5. There are a few changes that impacted Javalin MVC. This document will summarize them for you.
Probably the biggest impact is that Javalin targets Java 11 now, to support using the latest servlet-api (5.0). Due to this, many javax.* dependencies are now jakarta.* dependencies.
For people using, be aware that Guice is still implementing the javax.* interfaces (see here). Javalin MVC will respect either @Inject annotation for the time being.
For JAX-RS, only the jakarta annotations are supported in Javalin MVC 5.x. I couldn't think of a reason why not to force an upgrade for this dependency. It's less code maintenance for me.
There's a new project on my GitHub showing how to wire up a realistic web application. It's not limited to Javalin MVC, but also shows ways to use Hibernate, log4j 2, pac4j, etc. It doesn't show how to host a realistic front-end, but feel free to ask if you need it.
Needless to say, the interfaces for BeforeActionHandler, AfterActionHandler, WsBeforeActionHandler, and WsAfterActionHandler were complicated. I have replaced the old interfaces, so that they take a single argument with no return values.
There's now a BeforeActionContext, AfterActionContext, WsBeforeActionContext, and WsAfterActionContext parameter. It provides access to the HttpContext / WsContext and arguments. The "before" context classes now provide a setCancelled(boolean) method to prevent controller actions from running. The "after" context classes now provide a setHandled(boolean) method to indicate that a thrown exception has been handled... Furthermore, the exception remains available for inspection by subsequent handlers - it can even be replaced if needed.
I discovered some bugs related to invalid code being generated when combining dependency injection with WebSockets. I created several new unit tests to cover these cases, so it won't crop up again.
I am not sure why, but Javalin renamed the WebSocket methods related to client disconnects from WsDisconnect* to WsClose*. I followed suit, to avoid any confusion. Sorry if this is an inconvenience. A quick search/replace should resolve it, hopefully.
In 4.x, I wanted to make the names for getting values from query strings, the path, cookies, headers, etc. more consistent. To avoid introducing a breaking change in a minor release, I waited until 5.x to remove these. They have been marked @Deprecated for a while, so now is the time to update your code if you haven't already done so.
The @FromBody annotation is a general-purpose annotation for saying that a value comes from the body of a request. There's no benefit to explicitly specifying it's JSON or binary data, since that's inferred from the context of the request. These have been marked @Deprecated for a while, so now is the time to update your code if you haven't done so already.
In Javalin 5.x, the previous OpenAPI implementation was tossed out, replaced with something new. The biggest thing to keep in mind is that this is a compile-time tool, which means a little more configuration in your Maven file with the benefit that's there's no runtime overhead involved. I suggest reading the OpenAPI tutorial provided or see how I set it up in my Javalin MVC starter project.
The good thing about this change is that I didn't need to do anything to make it work. The OpenAPI annotations work perfectly fine on the controller methods, where before I needed to "move" them onto the Javalin route definitions.