Automatically publish Swagger :consumes for :form params

Make parameters-middleware publish swagger data for endpoints when
:form, but not :body params,
are present.

modules/reitit-middleware/src/reitit/ring/middleware/parameters.clj

@@ -10,4 +10,8 @@
   :form-params  - a map of parameters from the body
   :params       - a merged map of all types of parameter"
   {:name ::parameters
+   :compile (fn [{:keys [parameters]} _]
+              (if (and (some? (:form parameters)) (nil? (:body parameters)))
+                {:data {:swagger {:consumes ["application/x-www-form-urlencoded"]}}}
+                {}))
    :wrap params/wrap-params})

test/clj/reitit/ring/middleware/parameters_test.clj

@@ -1,7 +1,8 @@
 (ns reitit.ring.middleware.parameters-test
   (:require [clojure.test :refer [deftest testing is]]
             [reitit.ring.middleware.parameters :as parameters]
-            [reitit.ring :as ring]))
+            [reitit.ring :as ring]
+            [reitit.swagger :as swagger]))
 
 (deftest parameters-test
   (let [app (ring/ring-handler
@@ -13,3 +14,22 @@
            (app {:request-method :get
                  :uri "/ping"
                  :query-string "kikka=kukka"})))))
+
+(deftest parameters-swagger-test
+  (let [app (ring/ring-handler
+              (ring/router
+                [["/form-params" {:post {:parameters {:form {:x string?}}
+                                         :handler identity}}]
+                 ["/body-params" {:post {:parameters {:body {:x string?}}
+                                        :handler identity}}]
+                 ["/swagger.json" {:get {:no-doc true
+                                        :handler (swagger/create-swagger-handler)}}]]
+                {:data {:middleware [parameters/parameters-middleware]}}))
+        spec (fn [path]
+               (-> {:request-method :get :uri "/swagger.json"}
+                   app
+                   (get-in [:body :paths path :post])))]
+    (testing "with form parameters"
+      (is (= ["application/x-www-form-urlencoded"] (:consumes (spec "/form-params")))))
+    (testing "with body parameters"
+      (is (= nil (:consumes (spec "/body-params")))))))