reitit/doc/ring/data_driven_middleware.md

Data-driven Middleware

Reitit supports first-class data-driven middleware via reitit.ring.middleware/Middleware records, created with reitit.ring.middleware/create function. The following keys have special purpose:

key	description
:name	Name of the middleware as qualified keyword (optional,recommended for libs)
:wrap	The actual middleware function of handler args? => request => response
:gen	Middleware compile function, see compiling middleware.

When routes are compiled, all middleware are expanded (and optionally compiled) into Middleware Records and stored in compilation results for later use (api-docs etc). For actual request processing, they are unwrapped into normal middleware functions and composed together producing zero runtime performance penalty. Middleware expansion is backed by reitit.middleware/IntoMiddleware protocol, enabling plain clojure(script) maps to be used.

A Record:

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

(def wrap2
  (middleware/create
    {:name ::wrap2
     :description "a nice little mw, takes 1 arg."
     :wrap wrap}))

As plain map:

;; plain map
(def wrap3
  {:name ::wrap3
   :description "a nice little mw, :api as arg"
   :wrap (fn [handler]
           (wrap handler :api))})

TODO

more!