ui.cljs

(def schema {:kb/parent {:db/type :db.type/ref}
             :kb/children {:db/cardinality :db.cardinality/one}})

(def conn
  (let [c (d/create-conn schema)
        {:keys [tempids]}
        (d/transact! c
                     [{:db/id -1
                       :title "Intermediate"
                       :tags #{:level}}
                      {:db/id -2
                       :title "Business"
                       :tags #{:theme}}
                      {:db/id -3
                       :tags #{:learn}}
                      {:db/id -4
                       :tags #{:practice}}])]
    (d/transact! c
                 [{:kb/children [(tempids -1)]}
                  {:kb/parent (tempids -1)
                   :kb/children [(tempids -2)]}
                  {:kb/parent (tempids -2)
                   :kb/children [(tempids -3) (tempids -3)]}])
    c))



(defn render-branch [e]
  (let [rel-node (first (:kb/_parent e))
        children (map (partial d/entity @conn) (:kb/children rel-node))]
    
    [:li
     [:pre (pr-str (dissoc (d/pull @conn '[*] (:db/id e))
                           :db/id))]
     [:ul
      (for [child children]
        ^{:key child} [render-branch child])]]))

(defn root []
  (let [root-nodes (mapcat first (d/q '[:find ?children
                                        :where [?e :kb/children ?children]
                                        (not [?e :kb/parent])]
                                      @conn))]
    [:div.content
     [:ul
      (for [e root-nodes]
        ^{:key e} [render-branch (d/entity @conn e)])]]))