(ns ^:figwheel-always refs-test.core
(:require [om.core :as om :include-macros true]
[om.dom :as dom :include-macros true]
[sablono.core :as html :refer-macros [html]]))
(enable-console-print!)
(def app-state
(atom {:items [{:text "cat"}
{:text "dog"}
{:text "bird"}]
:selected-item {}}))
(defn selected-item []
(om/ref-cursor (:selected-item (om/root-cursor app-state))))
(defn
selected-item-title
[_ owner]
(reify
om/IRender
(render [_]
(html
[:div
(let [selected (om/observe owner (selected-item))]
(if (empty? selected)
[:h1 "Nothing selected"]
[:h1 (:text selected)]))]))))
(defn
selected-item-button
[item owner]
(reify
om/IRender
(render [_]
(html
[:li
[:button {:on-click
(fn []
(om/update! (om/root-cursor app-state) :selected-item item) ;; this doesn't update
;;(om/update! (om/root-cursor app-state) :selected-item (merge item {:foo 1})) ;; this does
)} (:text item)]]))))
(defn
root
[cursor owner]
(reify
om/IRender
(render [_]
(html
[:div
(om/build selected-item-title {})
[:ul
(om/build-all selected-item-button (:items cursor))]]))))
(om/root root app-state
{:target (.getElementById js/document "app")})
(https://www.refheap.com/108491)
The (selected-item) function crerates a ref-cursor which tracks the :selected-item key in app-state. When you click a selected-item-button the title changes to reflect the new value that has been put into the map. However, this only works once. Pressing a different button does not cause the title to re-render again so the title is always stuck at the value of the first button you pressed.
Although, simply adding a merge with an additional keyword seems to make it work... (merging with an empty map doesn't work either, tried that!)
Is my understanding on ref cursors wrong?
