Create a gist now

Instantly share code, notes, and snippets.

A version of castra.cljs without jquery
;; Copyright (c) Alan Dipert and Micha Niskin. All rights reserved.
;; The use and distribution terms for this software are covered by the
;; Eclipse Public License 1.0 (
;; which can be found in the file epl-v10.html at the root of this distribution.
;; By using this software in any fashion, you are agreeing to be bound by
;; the terms of this license.
;; You must not remove this notice, or any other, from this software.
(ns upgradingdave.castra
(:require [cognitect.transit :as t]
[ :as gxhr])
(:import [goog.async Deferred]
[goog Promise]))
;; helpers ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(defn- safe-pop
(or (try (pop x) (catch js/Error e)) x))
(defn- assoc-when
[m k v]
(if-not v m (assoc m k v)))
;; public api ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(def ^:dynamic *validate-only*
"Only validate request parameters, don't actually do it?"
(defn ex?
"Returns true if x is an ExceptionInfo."
(instance? ExceptionInfo x))
(defn make-ex
"Given either an existing exception or a map, returns an ExceptionInfo
object with the special status and serverStack properties set. If ex is
an exception already then ex itself is returned."
(if (ex? ex)
(let [{:keys [status message data stack cause]} ex]
(doto (ex-info message (or data {}) cause)
(aset "serverStack" stack)
(aset "status" status)))))
(defn- xhr-resp-headers
[xhr headers]
(reduce #(if-let [x (.getResponseHeader xhr %2)] (assoc %1 %2 x) %1) {} headers))
(defn ajax-fn
"Ajax request implementation using Closure ajax machinery."
[{:keys [url timeout credentials headers body]}]
(let [opts (-> {"headers" (merge
"timeoutMs" timeout}
;; TODO: test credentials
(assoc-when "withCredentials" credentials))
resp (fn [x]
{:status (.-status x)
:status-text (.-statusText x)
:body (.-responseText x)
:headers (xhr-resp-headers
["X-Castra-Tunnel" "X-Castra-Session"])})]
(-> (gxhr/send "POST" url (clj->js body) (clj->js opts))
;; resolve will receive the xhr
(fn [x] (resp x))
;; TODO need to test this
;; reject will receive a xhr.HttpError or xhr.Error on network error
(fn [x] (resp x))))
(def ^:private storage-key (str ::session))
(defn- get-session [ ] (.getItem js/localStorage storage-key))
(defn- set-session [x] (if (= x "DELETE")
(.removeItem js/localStorage storage-key)
(when x (.setItem js/localStorage storage-key x))))
(defn ajax
[{:keys [ajax-fn clj->json json->clj on-error] :as opts} expr]
(let [headers (-> {"X-Castra-Csrf" "true"
"X-Castra-Tunnel" "transit"
"X-Castra-Validate-Only" (str (boolean *validate-only*))
"Accept" "application/json"}
(assoc-when "X-Castra-Session" (get-session)))
body (if (string? expr) expr (clj->json expr))
wrap-ex #(make-ex {:message "Server Error" :cause %})
ajax-ex #(wrap-ex (make-ex {:status %1 :message %2}))
prom' (ajax-fn (merge opts {:headers headers :body body}))
resp #(-> (json->clj %)
(try (catch js/Error e {:error (wrap-ex e)})))]
(-> prom'
(fn [{:keys [headers body]}]
(set-session (get headers "X-Castra-Session"))
(let [{:keys [ok error]} (resp body)]
(or (and (not error) ok)
(doto (make-ex error) on-error))))
(fn [{:keys [headers body status status-text]}]
(doto (ajax-ex status status-text) on-error))))))
(defn with-default-opts
[& [opts]]
(->> opts (merge {:timeout 0
:credentials true
:on-error identity
:ajax-fn ajax-fn
:json->clj (partial t/read (t/reader :json))
:clj->json (partial t/write (t/writer :json))
:url (.. js/window -location -href)})))
(defn mkremote
"Given state error and loading input cells, returns an RPC function. The
optional :url keyword argument can be used to specify the URL to which the
POST requests will be made."
[endpoint state error loading & [opts]]
(fn [& args]
(let [live? (not *validate-only*)
prom (Promise.withResolver)
unload #(vec (remove (partial = prom) %))]
(when live? (swap! loading (fnil conj []) prom))
(let [prom' (-> (ajax
(with-default-opts opts) `[~endpoint ~@args])
#(do (when live?
(reset! error nil)
(reset! state %))
(.resolve prom))
#(do (when live? (reset! error %))
(.reject prom)))
#(when live? (swap! loading unload))))]
(doto prom (aset "xhr" prom'))
(defn- mkremote
"Given app db, returns a castra RPC function that can be used as a
re-frame handler."
[endpoint path & [opts]]
(fn [db [_ args]]
(let [prom (Promise.withResolver)
unload #(vec (remove (partial = prom) %))]
(let [prom' (-> (ajax
(with-default-opts opts) `[~endpoint ~args])
(dispatch [:process-response [path %1]])
(.resolve prom))
(dispatch [:bad-response path %1])
(.reject prom)))
#(dispatch [:finish-response unload])))]
(update-in db [:loading] #(conj (or % [])
(doto prom (aset "xhr" prom')))))
;; TODO: I think it might be better if all rpc calls return session
;; state? Need to think about authentication some more.
(fn [db [_ [path resp]]]
;; The server might send a valid response, but the response will
;; contain an exception object rather than the expected data.
(if-let [e (ex-data resp)]
;; this probably means cookie session expired
(= (:photos.api/msg e) "unauthorized")
(-> db
(assoc-in path nil)
(assoc-in [:user] nil)
(assoc-in [:error] e))
(-> db
(assoc-in path nil)
(assoc-in [:error] e)))
;; success!
(assoc-in db path resp))))
;; If there's a problem with the http request (network failure or
;; something strange) then this will get triggered.
;; TODO this has not been tested
(fn [db [path resp]]
;; (js/console.error "BAD RESPONSE")
(fn [db [unload]]
(update-in db [:loading] unload)))

I really like the ideas and design of castra. I was experimenting with using it on a personal project where I used reagent. Since nothing else in the project required jquery, I wondered if I could remove the dependency on jquery from the castra.cljs. Here's what I came up with. It uses, goog.async.Deferred, and goog.Promise, instead of jquery deferred, async and promises .

I just took core.cljs from the castra project, copied and pasted and changed it to work. But with a little extra work, I think this could be tweaked so that jquery is optional (but still leave it as the default).

Maybe have two separate implementations of ajax-fn: a jquery-ajax-fn and a goog-ajax-fn or something along those lines.


Also, the custom version of the mkremote function in mkremote.cljs above works with the reframe library.

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment