Router option to handle conflicts

README.md

@@ -393,13 +393,14 @@ Authorized access to guarded route:
 Routers can be configured via options. Options allow things like [`clojure.spec`](https://clojure.org/about/spec) validation for meta-data and fast, compiled handlers. The following options are available for the `reitit.core/router`:
 
   | key          | description |
-  | -----------|-------------|
+  | -------------|-------------|
   | `:path`      | Base-path for routes (default `""`)
   | `:routes`    | Initial resolved routes (default `[]`)
   | `:meta`      | Initial expanded route-meta vector (default `[]`)
   | `:expand`    | Function of `arg opts => meta` to expand route arg to route meta-data (default `reitit.core/expand`)
   | `:coerce`    | Function of `route opts => route` to coerce resolved route, can throw or return `nil`
   | `:compile`   | Function of `route opts => handler` to compile a route handler
+  | `:conflicts` | Function of `[route route] => side-effect` to handle conflicting routes (default `reitit.core/throw-on-conflicts!`)"
 
 ## Special thanks
 

src/reitit/core.cljc

@@ -66,6 +66,12 @@
       (or (some #(if (impl/conflicting-routes? r %) [r %]) rest)
           (recur rest)))))
 
+(defn throw-on-conflicts! [routes]
+  (throw
+    (ex-info
+      (str "router contains conflicting routes: " routes)
+      {:routes routes})))
+
 (defn name-lookup [[_ {:keys [name]}] opts]
   (if name #{name}))
 
@@ -103,7 +109,8 @@
   {:lookup name-lookup
    :expand expand
    :coerce (fn [route _] route)
-   :compile (fn [[_ {:keys [handler]}] _] handler)})
+   :compile (fn [[_ {:keys [handler]}] _] handler)
+   :conflicts throw-on-conflicts!})
 
 (defn linear-router
   "Creates a [[LinearRouter]] from resolved routes and optional
@@ -192,17 +199,21 @@
   [[LookupRouter]]. The following options are available:
 
   | key          | description |
-  | -----------|-------------|
+  | -------------|-------------|
   | `:path`      | Base-path for routes (default `\"\"`)
   | `:routes`    | Initial resolved routes (default `[]`)
   | `:meta`      | Initial expanded route-meta vector (default `[]`)
   | `:expand`    | Function of `arg opts => meta` to expand route arg to route meta-data (default `reitit.core/expand`)
   | `:coerce`    | Function of `route opts => route` to coerce resolved route, can throw or return `nil`
-  | `:compile` | Function of `route opts => handler` to compile a route handler"
+  | `:compile`   | Function of `route opts => handler` to compile a route handler
+  | `:conflicts` | Function of `[route route] => side-effect` to handle conflicting routes (default `reitit.core/throw-on-conflicts!`)"
   ([data]
    (router data {}))
   ([data opts]
    (let [opts (meta-merge default-router-options opts)
          routes (resolve-routes data opts)]
+     (when-let [conflicts (:conflicts opts)]
+       (when-let [conflicting-routes (first-conflicting-routes routes)]
+         (conflicts conflicting-routes)))
      ((if (some impl/contains-wilds? (map first routes))
         linear-router lookup-router) routes opts))))

test/cljc/reitit/core_test.cljc

@@ -1,8 +1,8 @@
 (ns reitit.core-test
   (:require [clojure.test :refer [deftest testing is are]]
-            [reitit.core :as reitit #?@(:cljs [:refer [Match]])])
+            [reitit.core :as reitit #?@(:cljs [:refer [Match Routing]])])
   #?(:clj
-     (:import (reitit.core Match)
+     (:import (reitit.core Match Routing)
               (clojure.lang ExceptionInfo))))
 
 (deftest reitit-test
@@ -171,4 +171,19 @@
            ["/a/*b"]]
 
     true [["/v2/public/messages/dataset/bulk"]
-          ["/v2/public/messages/dataset/:dataset-id"]]))
+          ["/v2/public/messages/dataset/:dataset-id"]])
+
+  (testing "router with conflicting routes"
+    (testing "throws by default"
+      (is (thrown-with-msg?
+            ExceptionInfo
+            #"router contains conflicting routes"
+            (reitit/router
+              [["/a"] ["/a"]]))))
+    (testing "can be configured to ignore"
+      (is (instance?
+            Routing
+            (reitit/router
+              [["/a"] ["/a"]]
+              {:conflicts (constantly nil)}))))))
+