Default Middleware

[metosin/reitit-middleware "0.4.1"]

Any Ring middleware can be used with reitit-ring, but using data-driven middleware is preferred as they are easier to manage and in many cases, yield better performance. reitit-middleware contains a set of common ring middleware, lifted into data-driven middleware.

• Parameter Handling
• Exception Handling
• Content Negotiation
• Multipart Request Handling
• Inspecting Middleware Chain

Parameters Handling

reitit.ring.middleware.parameters/parameters-middleware to capture query- and form-params. Wraps ring.middleware.params/wrap-params.

NOTE: will be factored into two parts: a query-parameters middleware and a Muuntaja format responsible for the the application/x-www-form-urlencoded body format.

Exception Handling

See Exception Handling with Ring.

Content Negotiation

Wrapper for Muuntaja middleware for content-negotiation, request decoding and response encoding. Takes explicit configuration via :muuntaja key in route data. Emit's swagger :produces and :consumes definitions automatically based on the Muuntaja configuration.

Negotiates a request body based on Content-Type header and response body based on Accept, Accept-Charset headers. Publishes the negotiation results as :muuntaja/request and :muuntaja/response keys into the request.

Decodes the request body into :body-params using the :muuntaja/request key in request if the :body-params doesn't already exist.

Encodes the response body using the :muuntaja/response key in request if the response doesn't have Content-Type header already set.

Expected route data:

key	description
:muuntaja	muuntaja.core/Muuntaja instance, does not mount if not set.

(require '[reitit.ring.middleware.muuntaja :as muuntaja])

• muuntaja/format-middleware - Negotiation, request decoding and response encoding in a single Middleware
• muuntaja/format-negotiate-middleware - Negotiation
• muuntaja/format-request-middleware - Request decoding
• muuntaja/format-response-middleware - Response encoding

(require '[reitit.ring :as ring])
(require '[reitit.ring.coercion :as rrc])
(require '[reitit.coercion.spec :as rcs])
(require '[ring.adapter.jetty :as jetty])

(def app
  (ring/ring-handler
    (ring/router
      [["/math"
        {:post {:summary "negotiated request & response (json, edn, transit)"
                :parameters {:body {:x int?, :y int?}}
                :responses {200 {:body {:total int?}}}
                :handler (fn [{{{:keys [x y]} :body} :parameters}]
                           {:status 200
                            :body {:total (+ x y)}})}}]
       ["/xml"
        {:get {:summary "forced xml response"
               :handler (fn [_]
                          {:status 200
                           :headers {"Content-Type" "text/xml"}
                           :body "<kikka>kukka</kikka>"})}}]]
      {:data {:muuntaja m/instance
              :coercion rcs/coercion
              :middleware [muuntaja/format-middleware
                           rrc/coerce-exceptions-middleware
                           rrc/coerce-request-middleware
                           rrc/coerce-response-middleware]}})))

(jetty/run-jetty #'app {:port 3000, :join? false})

Testing with httpie:

> http POST :3000/math x:=1 y:=2

HTTP/1.1 200 OK
Content-Length: 11
Content-Type: application/json; charset=utf-8
Date: Wed, 22 Aug 2018 16:59:54 GMT
Server: Jetty(9.2.21.v20170120)

{
 "total": 3
}

> http :3000/xml

HTTP/1.1 200 OK
Content-Length: 20
Content-Type: text/xml
Date: Wed, 22 Aug 2018 16:59:58 GMT
Server: Jetty(9.2.21.v20170120)

<kikka>kukka</kikka>

Multipart Request Handling

Wrapper for Ring Multipart Middleware. Emits swagger :consumes definitions automatically.

Expected route data:

key	description
[:parameters :multipart]	mounts only if defined for a route.

(require '[reitit.ring.middleware.multipart :as multipart])

• multipart/multipart-middleware a preconfigured middleware for multipart handling
• multipart/create-multipart-middleware to generate with custom configuration

Inspecting Middleware Chain

reitit.ring.middleware.dev/print-request-diffs is a middleware chain transforming function. It prints a request and response diff between each middleware. To use it, add the following router option:

:reitit.middleware/transform reitit.ring.middleware.dev/print-request-diffs

Partial sample output:

Example app

See an example app with the default middleware in action: https://github.com/metosin/reitit/blob/master/examples/ring-swagger/src/example/server.clj.