Handle middleware as data

Fixes metosin#202
Fixes metosin#190

Author: Deraen

CHANGELOG.md

@@ -52,9 +52,14 @@
 Previously required a `type => matcher` map. Options are checked against `type => matcher` coercion input, and a
 descriptive error is thrown when api is created with the old options format.
 
-* **TODO**: Middlewares
-
-* **BREAKING** Renamed `middlewares` to `middleware` and `:middlewares` metahandler to `:middleware`
+* **BREAKING**: Renamed `middlewares` to `middleware` and `:middlewares` metahandler to `:middleware`
+
+* **BREAKING**: Middleware must be defined as data: both our forms take a vector
+of middleware containing either a) fully configured mws (function)
+or b) a middleware templates in form [function args]. Nothing new, just best practices.
+  * You can also use anonymous functions to create middleware with correct parameters:
+  `(middleware [#(wrap-foo % {:opts :bar})])`
+  * Similar to [duct](https://github.com/weavejester/duct/wiki/Components#handlers)
 
 ### Migration guide
 

src/compojure/api/core.clj

@@ -33,13 +33,24 @@
   (let [handlers (keep identity handlers)]
     (routes/create nil nil {} nil (ring-handler handlers))))
 
+(defn middleware-fn [middleware]
+  (if (vector? middleware)
+    (let [[f & arguments] middleware]
+      #(apply f % arguments))
+    middleware))
+
+(defn compose-middleware [middleware]
+  (->> middleware
+       (map middleware-fn)
+       (apply comp identity)))
+
 (defmacro middleware
   "Wraps routes with given middlewares using thread-first macro."
   [middleware & body]
-  (let [middleware (reverse middleware)
-        routes? (> (count body) 1)]
-    `(let [body# ~(if routes? `(routes ~@body) (first body))]
-       (routes/create "" nil {} [body#] (-> body# ~@middleware)))))
+  (let [routes? (> (count body) 1)]
+    `(let [body# ~(if routes? `(routes ~@body) (first body))
+           wrap-mw# (compose-middleware ~middleware)]
+       (routes/create "" nil {} [body#] (wrap-mw# body#)))))
 
 (defmacro context [& args] (meta/restructure nil      args {:routes 'routes}))
 

src/compojure/api/meta.clj

@@ -251,7 +251,7 @@
 
 ; Applies the given vector of middlewares to the route
 (defmethod restructure-param :middleware [_ middleware acc]
-  (assert (and (vector? middleware) (every? (comp ifn? eval) middleware)))
+  (assert (and (vector? middleware) (every? #(or (and (vector? %1) (ifn? (first %1))) (ifn? %1)) middleware)))
   (update-in acc [:middleware] into (reverse middleware)))
 
 ; Bind to stuff in request components using letk syntax
@@ -260,7 +260,7 @@
 
 ; route-specific override for coercers
 (defmethod restructure-param :coercion [_ coercion acc]
-  (update-in acc [:middleware] conj `(mw/wrap-coercion ~coercion)))
+  (update-in acc [:middleware] conj [mw/wrap-coercion coercion]))
 
 ;;
 ;; Impl
@@ -293,11 +293,16 @@
 ;; Api
 ;;
 
-(defmacro route-middleware
-  "Wraps route body in mock-handler and middlewares."
-  [middleware body arg]
-  (let [middleware (reverse middleware)]
-    `((-> (fn [~arg] ~body) ~@middleware) ~arg)))
+(defn middleware-fn [middleware]
+  (if (vector? middleware)
+    (let [[f & arguments] middleware]
+      #(apply f % arguments))
+    middleware))
+
+(defn compose-middleware [middleware]
+  (->> (reverse middleware)
+       (map middleware-fn)
+       (apply comp identity)))
 
 (defn- destructure-compojure-api-request
   "Returns a vector of four elements:
@@ -322,7 +327,7 @@
 
 (defn restructure [method [path arg & args] {:keys [routes]}]
   (let [[parameters body] (extract-parameters args)
-        [lets letks responses middleware] [[] [] nil nil]
+        [lets letks responses middleware] [[] [] nil []]
         [path-string lets arg-with-request arg] (destructure-compojure-api-request path lets arg)
 
         {:keys [lets
@@ -342,7 +347,10 @@
         form `(~wrap ~@body)
         form (if (seq letks) `(letk ~letks ~form) form)
         form (if (seq lets) `(let ~lets ~form) form)
-        form (if (seq middleware) `(route-middleware ~middleware ~form ~arg) form)
+        form (if (seq middleware)
+               `(let [wrap-mw# (compose-middleware ~middleware)]
+                  ((wrap-mw# (fn [~arg] ~form)) ~arg))
+               form)
         form (if routes
                `(compojure.core/context ~path ~arg-with-request ~form)
                (compojure.core/compile-route method path arg-with-request (list form)))

test/compojure/api/integration_test.clj

@@ -79,13 +79,13 @@
 
 (facts "middleware"
   (let [app (api
-              (middleware [middleware* (middleware* 2)]
+              (middleware [middleware* [middleware* 2]]
                 (context "/middlewares" []
                   (GET "/simple" req (reply-mw* req))
-                  (middleware [(middleware* 3) (middleware* 4)]
+                  (middleware [[middleware* 3] [middleware* 4]]
                     (GET "/nested" req (reply-mw* req))
                     (GET "/nested-declared" req
-                      :middleware [(middleware* 5) (middleware* 6)]
+                      :middleware [[middleware* 5] [middleware* 6]]
                       (reply-mw* req))))))]
 
     (fact "are applied left-to-right"
@@ -108,7 +108,7 @@
               (GET "/first" []
                 (ok {:value "first"}))
               (GET "/second" []
-                :middleware [(constant-middleware (ok {:value "foo"}))]
+                :middleware [[constant-middleware (ok {:value "foo"})]]
                 (ok {:value "second"}))
               (GET "/third" []
                 (ok {:value "third"})))]
@@ -520,7 +520,7 @@
               (swagger-docs)
               (GET "/middleware" []
                 :query-params [x :- String]
-                :middleware [(constant-middleware (ok 1))]
+                :middleware [[constant-middleware (ok 1)]]
                 (ok 2)))]
 
     (fact "api-docs"
@@ -1050,7 +1050,7 @@
 
 (fact "more swagger-data can be (deep-)merged in - either via swagger-docs at runtime via mws, fixes #170"
   (let [app (api
-              (middleware [(rsm/wrap-swagger-data {:paths {"/runtime" {:get {}}}})]
+              (middleware [[rsm/wrap-swagger-data {:paths {"/runtime" {:get {}}}}]]
                 (swagger-docs
                   {:info {:version "2.0.0"}
                    :paths {"/extra" {:get {}}}})