Clojurians Log v2

Hi everyone, -- some beginner questions! -- Conceptual question (I'm just starting with reitit) - I've used an existing app which uses compojure as a model and got a basic example working using reitit.ring/router & reitit.ring/ring-handler). I see that reitit.ring/router is "a higher order router adding support for request method, handlers and middleware", and I note this means defining all of those things as data in the route defs. i.e. middleware defined as data alongside the routes, in contrast to the middleware stack applied to the whole router at once (commonly using the thread first macro), which we are familiar with in basic ring/compojure usage. So with that router, I then pass it to the reitit.ring/ring-handler, which, according to the docs "will return a valid ring handler". But my base assumption is that "a valid ring handler" is just a plain clojure function (allbeit conforming to the ring spec, i.e. receiving a request map and returning a response map). So what does it mean to say that ring-handler "returns a valid ring handler", if the latter is just a clojure function? I'm not clear what ring-handler's purpose is or what it's doing. Had a look at the source, but still not obvious to me.

Conceptual question #2 - comparing reitit.core and reitit.ring, and the fact that support for handlers, middleware and request methods are added by reitit.ring (thereby not present reitit.core), is that because none of those three ideas are applicable to a router when used from ClojureScript? (I have limited experience with front end routing so far). thanks :)

just sharing thought process here, but does the ring spec say or imply that middleware only wraps the top level handler ('app'), and not individual handlers or groups of handlers? with reitit's ability to state middleware as data in route definitions (and presumably also at the top level) mean that middleware is indeed now applied only to some handlers and not others?

So essentially if reitit-ring/router is not something I can use on its own, and I must always convert it to a handler by wrapping it with ring-handler, why is router itself exposed to the consumer at all? Also when I add middleware as options to ring-handler, is that identical in effect to wrapping the resulting handler, as traditionally done with ring middleware & thread-first? Just trying to smash this down to the simplest possible example.

When I try to pass a reitit-ring/router directly to the jetty adapter, that fails, it says "expects a function, you gave me an object" (if i interpret the error message correctly).

Hi @michaelkw, reitit is a relatively “low level” library that contains utilities for building routers for any need. That’s why there are many smaller pieces that can be assembled together. reitit.core contains just the “routing” part and doesn’t care about other concerns too much. Ring is a specification for handling HTTP requests and reitit.ring implements that specification with all kinds of options that you can fine-tune.

Thanks @valtteri, so exploring further, (and you've just answered this in part already, in a comment above) I can do -

(def app
  (-> ["/mail-settings"
       {:get mail-settings :post mail-settings}]
      ring/router          ; reitit router is a great big object
      ring/ring-handler    ; but for ring it must be a function
      (wrap-defaults site-defaults)))  ; ring middleware in traditional way, wrapping all routes

@michaelkw this is a working example of using reitit and reitit ring to create an API service. The routing is configured in `router.clj https://github.com/practicalli/gameboard-donut` Middleware can be used for all routes or added directly onto a specific route