add coercion for numeric params

src/tbd/core.clj

@@ -5,7 +5,12 @@
             [reitit.ring :as ring]
             [reitit.swagger :as swagger]
             [reitit.swagger-ui :as swagger-ui]
+            [reitit.coercion]
+            [reitit.coercion.malli :as malli]
+            [reitit.ring.coercion :as coercion]
+            [reitit.ring.middleware.exception :as exception]
             [reitit.ring.middleware.muuntaja :as muuntaja-middleware]
+            [reitit.ring.middleware.parameters :as parameters]
             [muuntaja.core :as m]
             [tbd.health.routes :as health]
             [tbd.math.routes :as math]))
@@ -21,6 +26,19 @@
           (and (map? (:body resp)) (nil? (:definitions (:body resp))))
           (update :body dissoc :definitions))))))
 
+(defn- coercion-error-handler
+  "Invalid request params -> 400 in the same EDN shape the routes use."
+  [e _req]
+  {:status 400
+   :headers {"Content-Type" "application/edn; charset=utf-8"}
+   :body (pr-str {:error "invalid request parameters"
+                  :details (:humanized (reitit.coercion/encode-error (ex-data e)))})})
+
+(def ^:private exception-middleware
+  (exception/create-exception-middleware
+    (assoc exception/default-handlers
+           :reitit.coercion/request-coercion coercion-error-handler)))
+
 ;; Each logical group (health, users, orders, ...) owns a `tbd.<group>.routes`
 ;; namespace that returns its own route subtree; they're concatenated here.
 (def router
@@ -37,7 +55,11 @@
      (health/routes)
      (math/routes)]
     {:data {:muuntaja m/instance
-            :middleware [muuntaja-middleware/format-middleware]}}))
+            :coercion malli/coercion
+            :middleware [parameters/parameters-middleware
+                         muuntaja-middleware/format-middleware
+                         exception-middleware
+                         coercion/coerce-request-middleware]}}))
 
 (def app
   (-> (ring/ring-handler

src/tbd/math/routes.clj

@@ -1,24 +1,24 @@
 (ns tbd.math.routes
   (:require [tbd.math.core :as math]))
 
-(defn- parse-num [s]
+;; :int first so "2" stays a long (a bare `number?` or :double would decode it to 2.0).
-  (when s
+;; The :swagger/* props make the spec say plain `number` instead of the first :or branch.
-    (or (parse-long s) (parse-double s))))
+(def ^:private number-schema
+  [:or {:swagger/type "number" :swagger/format "double"} :int :double])
 
 (defn- edn-response [status body]
   {:status status
    :headers {"Content-Type" "application/edn; charset=utf-8"}
    :body (pr-str body)})
 
-(defn- add-handler [{:keys [query-params]}]
+(defn- add-handler [{{{:keys [x y]} :query} :parameters}]
-  (let [x (parse-num (get query-params "x"))
+  (edn-response 200 {:result (math/add x y)}))
-        y (parse-num (get query-params "y"))]
-    (if (and x y)
-      (edn-response 200 {:result (math/add x y)})
-      (edn-response 400 {:error "x and y query params are required and must be numbers"}))))
 
 (defn routes []
   ["/api/add"
    {:get {:tags ["math"]
           :summary "Add two numbers (?x=2&y=3 => {:result 5})"
+          :parameters {:query [:map
+                               [:x {:description "First addend"} number-schema]
+                               [:y {:description "Second addend"} number-schema]]}
           :handler add-handler}}])

test/tbd/math/routes_test.clj

@@ -1,16 +1,12 @@
 (ns tbd.math.routes-test
   (:require [clojure.edn :as edn]
             [clojure.test :refer [deftest is testing]]
-            [reitit.ring :as ring]
+            [muuntaja.core :as m]
-            [ring.middleware.params :refer [wrap-params]]
+            [tbd.core :as core]))
-            [tbd.math.routes :as math]))
-
-;; wrap-params populates :query-params, as wrap-defaults does in tbd.core.
-(def handler
-  (wrap-params (ring/ring-handler (ring/router (math/routes)))))
 
+;; Coercion/validation is configured on the router in tbd.core, so go through the real app.
 (defn add [query]
-  (let [resp (handler {:request-method :get :uri "/api/add" :query-string query})]
+  (let [resp (core/app {:request-method :get :uri "/api/add" :query-string query})]
     (-> resp
         (update :body edn/read-string))))
 
@@ -27,4 +23,19 @@
     (doseq [query [nil "x=2" "y=3" "x=abc&y=3" "x=2&y=abc"]]
       (let [resp (add query)]
         (is (= 400 (:status resp)) (str "query: " query))
+        (is (= "application/edn; charset=utf-8" (get-in resp [:headers "Content-Type"])))
         (is (contains? (:body resp) :error))))))
+
+(deftest add-route-swagger-test
+  (let [spec (-> (core/app {:request-method :get :uri "/swagger.json"
+                            :headers {"accept" "application/json"}})
+                 :body
+                 (->> (m/decode "application/json")))
+        params (->> (:paths spec)
+                    (some (fn [[path v]] (when (= "/api/add" (str (namespace path) "/" (name path))) v)))
+                    :get
+                    :parameters)]
+    (testing "x and y are documented as required numeric query params"
+      (is (= [{:name "x" :in "query" :type "number" :required true}
+              {:name "y" :in "query" :type "number" :required true}]
+             (map #(select-keys % [:name :in :type :required]) params))))))