Clojurians Log v2

And I'm talking about gzip'ing responses.

yes, that's a bit tricky

you want a per-route middleware (gzip) to run after a common middleware (response coercion)

Yup

you need to have a common gzip middleware that runs after response coercion, and then some sort of conditional in there

so you can't use ring.middleware.gzip as-is

this is a good fit for data-driven reitit middleware, actually

https://github.com/metosin/reitit/blob/master/doc/ring/compiling_middleware.md#require-keys-on-routes-at-creation-time

so you have a middleware with a :compile that can then use the route data to either do something or not

Great! I'll take a deep look 👀

So, basically I 1. define a route with data, eg {:gzip true} 2. mount gzip-middleware as the last middleware in the common route options 3. check for existense of the :gzip key in middleware 4. if it exists, return ring.middleware.gzip/wrap-gzip ?

yeah something like that

(def gzip-response-middleware
  {:name ::gzip-response-middleware
   :compile
   (fn [route-data _opts]
     (when-let [_gzip (:gzip route-data)]
       ring.middleware.gzip/wrap-gzip))})

:data {:muuntaja muuntaja/instance
            :middleware [wrap-internal-error
                         swagger/swagger-feature
                         openapi/openapi-feature
                         middleware.muuntaja/format-negotiate-middleware
                         middleware.muuntaja/format-response-middleware
                         middleware.muuntaja/format-request-middleware
                         middleware.parameters/parameters-middleware
                         coercion/coerce-request-middleware
                         gzip-response-middleware]
            :coercion (reitit.coercion.malli/create
                       {;; set of keys to include in error messages
                        :error-keys #{:value :humanized #_:type :errors  #_:transformed}
                        ;; validate request & response
                        :validate true
                        ;; top-level short-circuit to disable request & response coercion
                        :enabled true
                        ;; strip-extra-keys (effects only predefined transformers)
                        :strip-extra-keys false
                        ;; add/set default values
                        :default-values true
                        ;; malli options
                        :options nil})}

Gunzipped data is clojure data, not a list of JSON objects

(don't mind both swagger and openapi 👀 , experimenting)

I can never remember which order :middleware is supposed to be in

I guess that should be the right order, the middleware gets run in-order

Me thinks so too

this is a great time to use middleware debugging: https://github.com/metosin/reitit/blob/master/doc/http/transforming_interceptor_chain.md#printing-context-diffs

https://clojurians-log.clojureverse.org/reitit/2021-04-06 > In ring, the middleware chain in run in reverse order. Inside reitit router, mw is run in reverse-reverse order, e.g. in "right" order. That did the trick. This is the correct order

:middleware [gzip-response-middleware
                         wrap-internal-error
                         swagger/swagger-feature
                         openapi/openapi-feature
                         middleware.muuntaja/format-negotiate-middleware
                         middleware.muuntaja/format-response-middleware
                         middleware.muuntaja/format-request-middleware
                         middleware.parameters/parameters-middleware
                         coercion/coerce-request-middleware]

Maybe this little nugget of information is precious enough to be repeated in Reitit docs? 😅

So just for the ref, if anyone else is looking for gzipping response payload after coercion this solution works.

right yes the execution order for :middleware [A B C] is:

request -> A -> B -> C -> handler -> C -> B -> A

Yup

I added a mention to the changelog

yes, looks like that

there's an RC out that you can try

https://github.com/metosin/reitit/releases/tag/0.8.0-alpha1