Add API documentation using OpenAPI and SwaggerUI

README.md

@@ -32,3 +32,5 @@ The following links proved more than useful when working on this assignment:
 * <https://clojurecivitas.github.io/malli/elements_of_malli.html>
 * <https://github.com/metosin/reitit/blob/master/doc/coercion/malli_coercion.md>
 * <https://cljdoc.org/d/com.github.seancorfield/next.jdbc/1.3.1086/doc/getting-started>
+* <https://cljdoc.org/d/metosin/reitit/0.10.0/doc/ring/swagger-support>
+* <https://www.baeldung.com/clojure-ring>

project.clj

@@ -1,5 +1,5 @@
-(defproject yohoho "0.1.0-SNAPSHOT"
-  :description "Yo-Ho-Ho, a take home assignment for the brave"
+(defproject yohoho "0.42.0"
+  :description "Yo-ho-ho, a take home assignment for the brave"
   :url "https://git.dromaludaire.info/yohoho"
   :license {:name "WTFPL – Do What the Fuck You Want to Public License"
             :url "https://www.wtfpl.net/about/"}
@@ -8,6 +8,8 @@
                  [ring/ring-jetty-adapter "1.15.3"]
                  [metosin/reitit "0.10.0"]
                  [metosin/reitit-malli "0.10.0"]
+                 [fi.metosin/reitit-openapi "0.10.0"]
+                 [metosin/reitit-swagger-ui "0.10.0"]
                  [metosin/muuntaja "0.6.11"]
                  [com.github.seancorfield/next.jdbc "1.3.1086"]
                  [org.xerial/sqlite-jdbc "3.51.1.0"]]

src/yohoho/core.clj

@@ -5,6 +5,8 @@
             [muuntaja.core :as m]
             [reitit.coercion.malli :as malli]
             [reitit.ring.coercion :as coercion]
+            [reitit.openapi :as openapi]
+            [reitit.swagger-ui :as swagger-ui]
             [next.jdbc :as jdbc]
             [next.jdbc.sql :as sql]
             [next.jdbc.result-set :as rs])
@@ -25,11 +27,38 @@
 
 (def Email [:re email-regexp])
 
-(def Item
+(def ItemInput
   [:map
    [:name :string]
    [:email Email]])
 
+(def Item
+  [:map
+   [:id :int]
+   [:name :string]
+   [:email Email]])
+
+(def ItemResponse Item)
+
+(def ItemsResponse
+  [:map
+   [:items [:vector Item]]])
+
+(def ErrorResponse
+  [:map
+   [:error :string]
+   [:message {:optional true} :string]])
+
+;; Those are generated by Malli when validation fails
+;; TODO: find a way to produce lighter messages on validation error
+;;       (maybe a custom middleware?)
+(def Error400Response
+  [:map
+   [:value :map]
+   [:type :string]
+   [:coercion :string]
+   [:in [:vector :string]]
+   [:humanized :map]])
 
 ;; Database stuff -------------------------------------------------
 (def db (:db config))
@@ -124,12 +153,45 @@
   (ring/ring-handler
    (ring/router
     [;; Health check
-     ["/ahoy"     {:get ahoy-handler}]
+     ["/ahoy"         {:get {:summary "Health check"
+                             :openapi {:tags ["Health"]}
+                             :handler ahoy-handler
+                             :responses {200 {:body :string
+                                              :description "Server is alive"}}}}]
      ;; The real assignment: create and retrieve items
-     ["/item/:id" {:get get-item-handler}]
-     ["/items"    {:get get-items-handler
-                   :post {:handler create-item-handler
-                          :parameters {:body Item}}}]]
+     ["/item/:id"     {:get {:summary "Get an item by id"
+                             :openapi {:tags ["Items"]}
+                             :handler get-item-handler
+                             :parameters {:path [:map [:id :int]]}
+                             :responses {200 {:body ItemResponse
+                                              :description "Item found"}
+                                         400 {:body Error400Response
+                                              :description "Invalid input"}
+                                         404 {:body ErrorResponse
+                                              :description "Item not found"}}}}]
+     ["/items"        {:get {:summary "Get all items"
+                             :openapi {:tags ["Items"]}
+                             :handler get-items-handler
+                             :responses {200 {:body ItemsResponse ;; TODO!
+                                              :description "List of all items"}}}
+                       :post {:summary "Create an item"
+                              :openapi {:tags ["Items"]}
+                              :handler create-item-handler
+                              :parameters {:body ItemInput}
+                              :responses {201 {:body Item
+                                               :description "Item created successfully"}
+                                          400 {:body Error400Response
+                                               :description "Invalid input"}
+                                          415 {:body ErrorResponse
+                                               :description "Unsupported media type"}}}}]
+     ;; OpenAPI routes
+     ["" {:no-doc true
+          :openapi {:info {:title "Yo-ho-ho API"
+                           :description "A take-home assignment for HolidayPirates"
+                           :version "0.42.0"}}}
+      ["/openapi.json" {:get (openapi/create-openapi-handler)}]
+      ["/doc/*"     {:get (swagger-ui/create-swagger-ui-handler {:url "/openapi.json"})}]]]
+
     ;; Middlewares:
     ;; - wrap-content-type-json: ensure POST routes are sent JSON payload
     ;; - muuntaja middleware to automatically decode JSON
@@ -141,10 +203,14 @@
                          coercion/coerce-exceptions-middleware
                          coercion/coerce-request-middleware
                          coercion/coerce-response-middleware]}})
+
+   (ring/routes
+    ;; Add trailing slash when missing, eg. for /doc
+    (ring/redirect-trailing-slash-handler {:method :add})
     ;; Default route: anything not explicitely handled should give a 404
     (ring/create-default-handler
      {:not-found (constantly {:status 404
-                             :body {:error "Not Found"}})})))
+                              :body {:error "Not Found"}})}))))
 
 
 ;; Entry point ----------------------------------------------------
@@ -156,4 +222,5 @@
     (println "Initializing SQLite database...")
     (init-db!)
     (println "Ahoy! Yo-ho-ho API starting on port" port)
+    (println "API documentation on /openapi.json and on /doc (interactive UI)")
     (http-server/run-jetty app {:port port})))