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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)))

upgradingdave commented Mar 3, 2016

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.


upgradingdave commented Mar 3, 2016

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

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