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ring in reitit documentation refers to ring application, not ring web server. You can use any as long as it is compatible with ring application. httpkit is compatible.

Thank you @delaguardo. So, to understand. Is there any server that would support running an app made of just a reitit router? What is the purpose of the standalone core router (as in not wrapped as a ring router) in real life?

I'm not aware of such server. But router itself is useful not only in the context of serving http responses. For example to handle messages in a queue, mimic defmulti with enriched context, etc.

I actually figured out how to use muuntaja eventually to parse the body and how one needs to enable it etc.

👍 🎉

The stack trace

; Tue Jul 08 19:32:46 BST 2025 [http-kit-server-worker-4] ERROR - GET /hello/nick
; clojure.lang.ExceptionInfo: Request coercion failed {:schema {:age Int, Keyword Any}, :errors (not (map? [nil])), :type :reitit.coercion/request-coercion, :coercion #Coercion{:name :schema}, :value nil, :in [:request :query-params], :request {:reitit.core/match #reitit.core.Match{:template "/hello/:name", :data {:coercion #Coercion{:name :schema}, :middleware [{:name :reitit.ring.coercion/coerce-request, :spec :reitit.spec/parameters, :compile #function[reitit.ring.coercion/fn--12869]}], :name :xyz.core/yolo, :get {:handler #function[xyz.core/hello-ctrl], :parameters {:path [{:name java.lang.String}], :query [{:age Int}]}}}, :result #reitit.ring.Methods{:get #reitit.ring.Endpoint{:data {:coercion #Coercion{:name :schema}, :middleware [{:name :reitit.ring.coercion/coerce-request, :spec :reitit.spec/parameters, :compile #function[reitit.ring.coercion/fn--12869]}], :name :xyz.core/yolo, :handler #function[xyz.core/hello-ctrl], :parameters {:path {:name java.lang.String}, :query {:age Int}}}, :handler #function[reitit.ring.coercion/fn--12869/fn--12871/fn--12872], :path "/hello/:name", :method :get, :middleware [#reitit.middleware.Middleware{:name :reitit.ring.coercion/coerce-request, :wrap #function[reitit.ring.coercion/fn--12869/fn--12871], :spec :reitit.spec/parameters}]}, :head nil, :post nil, :put nil, :delete nil, :connect nil, :options #reitit.ring.Endpoint{:data {:coercion #Coercion{:name :schema}, :middleware [{:name :reitit.ring.coercion/coerce-request, :spec :reitit.spec/parameters, :compile #function[reitit.ring.coercion/fn--12869]}], :name :xyz.core/yolo, :no-doc true, :handler #function[reitit.ring/fn--12600/fn--12609]}, :handler #function[reitit.ring/fn--12600/fn--12609], :path "/hello/:name", :method :options, :middleware [#reitit.middleware.Middleware{:name :reitit.ring.coercion/coerce-request, :wrap nil, :spec :reitit.spec/parameters}]}, :trace nil, :patch nil}, :path-params {:name "nick"}, :path "/hello/nick"}, :reitit.core/router #object[reitit.core$mixed_router$reify__11754 0x70dbf017 "reitit.core$mixed_router$reify__11754@70dbf017"], :remote-addr "0:0:0:0:0:0:0:1", :start-time 932866731487291, :headers {"accept" "*/*", "host" "localhost:9393", "user-agent" "curl/8.7.1"}, :async-channel #object[org.httpkit.server.AsyncChannel 0x74e46ad4 "/[0:0:0:0:0:0:0:1]:9393<->/[0:0:0:0:0:0:0:1]:57012"], :server-port 9393, :content-length 0, :websocket? false, :content-type nil, :character-encoding "utf8", :uri "/hello/nick", :server-name "localhost", :query-string "age=37", :path-params {:name "nick"}, :body nil, :scheme :http, :request-method :get}}
; 	at reitit.coercion$request_coercion_failed_BANG_.invokeStatic(coercion.cljc:51)
; 	at reitit.coercion$request_coercion_failed_BANG_.invoke(coercion.cljc:49)
; 	at reitit.coercion$request_coercer$fn__12142.invoke(coercion.cljc:105)
; 	at reitit.coercion$coerce_request$fn__12182.invoke(coercion.cljc:142)
; 	at clojure.lang.PersistentArrayMap.kvreduce(PersistentArrayMap.java:475)
; 	at clojure.core$fn__8559.invokeStatic(core.clj:6987)
; 	at clojure.core$fn__8559.invoke(core.clj:6967)
; 	at clojure.core.protocols$fn__8287$G__8282__8296.invoke(protocols.clj:174)
; 	at clojure.core$reduce_kv.invokeStatic(core.clj:6998)
; 	at clojure.core$reduce_kv.invoke(core.clj:6989)
; 	at reitit.coercion$coerce_request.invokeStatic(coercion.cljc:140)
; 	at reitit.coercion$coerce_request.invoke(coercion.cljc:139)
; 	at reitit.ring.coercion$fn__12869$fn__12871$fn__12872.invoke(coercion.cljc:40)
; 	at reitit.ring$ring_handler$fn__12708.invoke(ring.cljc:386)
; 	at 

> I really don't know how to read this Just to answer this part, the error is saying it found the value [nil] where it expected a keyword map.

Right, I've even copy pasted the example from here https://cljdoc.org/d/metosin/reitit/0.9.1/doc/ring/pluggable-coercion and it works if called programmatically but trying to use curl or httpie it fails with the above exception. My curl is

curl -v POST -H "Content-type: text/plain" -d "y=6" ""

http POST "" y=5

Which example did you use, as there are several on the page.

The one under Full Example

(require '[reitit.ring.coercion :as rrc])
(require '[reitit.coercion.schema])
(require '[reitit.ring :as ring])
(require '[schema.core :as s])

(def PositiveInt (s/constrained s/Int pos? 'PositiveInt))

(def app
  (ring/ring-handler
    (ring/router
      ["/api"
       ["/ping" {:name ::ping
                 :get (fn [_]
                        {:status 200
                         :body "pong"})}]
       ["/plus/:z" {:name ::plus
                    :post {:coercion reitit.coercion.schema/coercion
                           :parameters {:query {:x s/Int}
                                        :body {:y s/Int}
                                        :path {:z s/Int}}
                           :responses {200 {:body {:total PositiveInt}}}
                           :handler (fn [{:keys [parameters]}]
                                      (let [total (+ (-> parameters :query :x)
                                                     (-> parameters :body :y)
                                                     (-> parameters :path :z))]
                                        {:status 200
                                         :body {:total total}}))}}]]
      {:data {:middleware [rrc/coerce-exceptions-middleware
                           rrc/coerce-request-middleware
                           rrc/coerce-response-middleware]}})))

I've tried modifying my curl Content-type and got to see the body value as a param using the middleware logger but still I have not managed to use the :body as whatever I do this key is not generated.

I can see y as a form param though using the default "application/x-www-form-urlencoded"

; --- :request :reitit.ring.middleware.parameters/parameters ---
; 
;   {:async-channel #<org.httpkit.server.AsyncChannel@64934162 /[0:0:0:0:0:0:0:1]:9393<->/[0:0:0:0:0:0:0:1]:60487>,
;    :body #<org.httpkit.BytesInputStream@64e1ea05 BytesInputStream[len=3]>,
;    :character-encoding "utf8",
;    :content-length 3,
;    :content-type "application/x-www-form-urlencoded",
;    :headers {"accept" "*/*",
;              "content-length" "3",
;              "content-type" "application/x-www-form-urlencoded",
;              "host" "localhost:9393",
;              "user-agent" "curl/8.7.1"},
;    :path-params {:z "2"},
;    :query-string "x=34",
;    :remote-addr "0:0:0:0:0:0:0:1",
;    :request-method :post,
;    :scheme :http,
;    :server-name "localhost",
;    :server-port 9393,
;    :start-time 946790008908541,
;    :uri "/api/plus/2",
;    :websocket? false,
;    +:form-params {"y" "6"},
;    +:params {"x" "34", "y" "6"},
;    +:query-params {"x" "34"}}

Here is a working version:

(ns xyz.core
  (:require
   [muuntaja.core :as m]
   [reitit.coercion.schema]
   [reitit.ring :as ring]
   [reitit.ring.coercion :as rrc]
   [ring.adapter.jetty9 :as jetty]
   [ring.middleware.params :as params]
   [schema.core :as schema])
  (:gen-class))

(defn hello-ctrl [req]
  (let [name (-> req :parameters :path :name)
        age (-> req :parameters :query :age)]
    (println req)
    {:status  200
     :headers {"Content-Type" "text/html"}
     :body    (str "Hello " name " :)\nAre you " age " years old?")}))

(defn default-handler [_]
  {:status  200
   :headers {"Content-Type" "text/html"}
   :body    "It's OK, yes!"})

(defn app2
  []
  (ring/ring-handler
   (ring/router
    [["/" {:get default-handler}]
     ["/hello/:name" {:name ::yolo
                      :get {:handler hello-ctrl
                            :parameters {:path {:name schema/Str}
                                         :query {:age schema/Int}}}}]]
    {:data {:muuntaja m/instance
            :coercion reitit.coercion.schema/coercion
            :middleware [params/wrap-params
                         rrc/coerce-request-middleware]}})))

(defn go
  []
  (jetty/run-jetty (fn [request] ((app2) request)) {:port 3001 :allow-null-path-info true :join? false}))

❯ curl \?age\=30
Hello nick :)
Are you 30 years old?%  

A few things:

You need ring to decode the params, that's what the params middleware is about

(however, you could, instead use this: [reitit.ring.middleware.parameters :as parameters])

(I use that, which just wraps rings params)

:middleware [
....
                        muuntaja/format-middleware
                        parameters/parameters-middleware
....]
...
...
...

Secondly, for repl usage, I wrap app2 into a function, so I can re-eval the form and not have to start/restart the server.

.

.

Hope that helps!

Have a look here:

.

Right, in between copy-pasta I forgot to post my latest version which was using

{:data {:middleware [reitit.ring.middleware.parameters/parameters-middleware
                         ring.middleware.keyword-params/wrap-keyword-params
                         rrc/coerce-request-middleware
                         rrc/coerce-response-middleware
                         rrc/coerce-exceptions-middleware
                         ]}

you're most welcome! 🙂 Good luck! 🙂

.

Sorry @dharrigan but is what you mean above that I could use

reitit.ring.middleware.parameters :as parameters

ring.middleware.params/wrap-params

does the request have content-type: application/json; charset=utf-8 header?