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 ยฉ 2014 David Nolen
Distributed under the Eclipse Public License either version 1.0 or (at your option) any later version.