Check if URL parameter exists in map

Question

(defroutes my-routes
  (GET "/:id" [id] (html/display-thing id)))

(def my-map
  {:id 1 :title "One"
   :id 2 :title "Two"})

Is there a nice way to check if the url parameter id exists in my-map else continue checking if the other routes match? I know you can do something similar with regex like so: ["/:id", :id #"[0-9]+"] and suspect it might be possible to plug in an arbitrary predicate function.

Answer 1

Not actually at a REPL, but isn't this as straightforward as returning nil from html/display-thing if there's no id element in my-map? Take a look at (source GET) to see how the macro passes control to the next route if the method or URL don't match.