I'm using ring-cors and trying to pass a cors-policy for the (wrap-cors) function. This is what my code looks like:
(def cors-policy
{:access-control-allow-origin [#"http://localhost:8080"]
:access-control-allow-methods [:get :put :post]})
(def dev-handler (-> #'japi/routes
wrap-reload
wrap-params
(wrap-cors cors-policy) ;; <- Here
wrap-json-response
(wrap-defaults api-defaults)
push-state/handle))
This results in an error:
No value supplied for key: {:access-control-allow-origin #{"http://localhost:8080"}, :access-control-allow-methods #{:get :post :put}}
Looking at the source code for (wrap-cors) it looks like the error is coming from trying to apply (hash-map) to my cors-policy map. It seems like I cannot pass a map definition but instead I have to pass the keys/values explicitly when calling (wrap-cors). Any ideas to work around this?
I've tried (apply hash-map cors-policy)
in the repl and that works fine, however when passing a dummy handler such as (wrap-cors identity cors-policy)
this again results in the same error.
Edit: cfrick's answer is correct, note however that I had to remove shadow-cljs' (push-state/handle) handler at the end of my dev-handler definition for my setup to work.
The wrapper uses a "pattern" that is sometimes seen and focuses on "human consumption" of the function. It takes the "rest" of the arguments and turns the pairs of it into a map. This is already "meh" for humans and is utterly bad for machines (e.g. to pass as arguments).
You have to do the call it like this:
(wrap-cors $handler :a 1 :b 2)
So the easiest way from here would be:
(def cors-policy
[:a 1
:b 2])
(apply wrap-cors $handler cors-policy)
Or if you want to stick with the map (IMHO a good approach), you have to flatten the map beforehand. e.g.
(apply wrap-cors $handler (into [] cat cors-policy))
But with the use of the threading macro ->
this becomes harder to do
now (->
is just a macro and the resulting code would be (apply $handler wrap-cors ...)
which is unintended.
So at this point I'd add my own defn
that just takes the handler
again. E.g. something like
(defn cors-wrapper
[handler config-map]
(apply wrap-cors handler (into [] cat config-map)))