gistfile1.txt

;; Given the following app state:
(def state {:items/list [{:item/id 0 :item/type :foo :foo/value 42}
                         {:item/id 1 :item/type :bar :bar/value 43}]})

;; Foo has property `:foo/value`
(defui Foo
  static om/Ident
  (ident [this {:keys [item/type item/id]}]
    [type id])
  static om/IQuery
  (query [this]
    [:item/id :item/type :foo/value]))

;; Bar has property `:bar/value`
(defui Bar
  static om/Ident
  (ident [this {:keys [item/type item/id]}]
    [type id])
  static om/IQuery
  (query [this]
    [:item/id :item/type :bar/value]))

;; An item can be either Foo or Bar
(defui Item
  static om/IQuery
  (query [this]
    {:foo (om/get-query Foo)
     :bar (om/get-query Bar)}))

;; The item list contains items (either Foo items or Bar items)
(defui ItemList
  static om/IQuery
  (query [this]
    [{:items/list (om/get-query Item)}]))

;; the entire (ItemList) query will then be:
[{:items/list {:foo [:item/id :item/type :foo/value]
               :bar [:item/id :item/type :bar/value]}}]