om-sync
A reusable synchronization component for Om.
Example
om-sync leverages the new :tx-listen option allowed by
om.core/root. For example you can imagine setting up your
application like so:
(let [tx-chan (chan)
tx-pub-chan (async/pub tx-chan (fn [_] :txs))]
(om-sync.util/edn-xhr
{:method :get
:url "/init"
:on-complete
(fn [res]
(reset! app-state res)
(om/root app-view app-state
{:target (gdom/getElement "app")
:shared {:tx-chan tx-pub-chan}
:tx-listen
(fn [tx-data root-cursor]
(put! tx-chan [tx-data root-cursor]))}))}))We publish a transaction queue channel :tx-chan as a global service
via :shared so that om-sync instances can listen in.
We can now take any application data and wrap it in an om-sync
instance. Whenever application data changes om-sync will synchronize
those changes via EDN requests to
a server.
Notice in the following that om-sync can take an :on-error
handler. This error handler will be given tx-data which contains
enough information to roll back the entire application state if
something goes wrong.
(defn app-view [app owner]
(reify
om/IWillUpdate
(will-update [_ next-props next-state]
(when (:err-msg next-state)
(js/setTimeout #(om/set-state! owner :err-msg nil) 5000)))
om/IRenderState
(render-state [_ {:keys [err-msg]}]
(dom/div nil
(om/build om-sync (:items app)
{:opts {:view items-view
:filter (comp #{:create :update :delete} tx-tag)
:id-key :some/id
:on-success (fn [res tx-data] (println res))
:on-error
(fn [err tx-data]
(reset! app-state (:old-state tx-data))
(om/set-state! owner :err-msg
"Ooops! Sorry something went wrong try again later."))}})
(when err-msg
(dom/div nil err-msg))))))om.core/transact! and om.core/update! now support tagging
transactions with a keyword or a vector that starts with a
keyword. om-sync listens in on transactions labeled :create,
:update, and :delete.
(defn foo [some-data owner]
(om.core/transact! some-data :foo (fn [_] :bar) :update))If you are given some component that does not tag its transactions or
the tags do not correspond to :create, :update, and :delete you
can provide a :tag-fn via :opts to om-sync so that you can
classify the transaction yourself.
Contributions
Pull requests welcome.
License
Copyright © 2014 David Nolen
Distributed under the Eclipse Public License either version 1.0 or (at your option) any later version.