Maybe I should just trigger the load for the user separately with the alias as an parameter and then, when the data is loaded, trigger the route change, not loading anything in the :will-enter fn

I think you'd likely need a component that uses the user alias in its ident in order for the router to not throw the error you mentioned. Then also have the server allow taking the alias as an ID when queries are issued (because on first load the client will not know this mapping) and then have an index table in the fulcro client db user-alias -> [:user/id <id>] This way you can keep using :user/id as the ident in all your other components and in the refs to users.

Your second comment might also work - I had to do something similar when my URL didn't match my fulcro-segment - will-enter always calls route-immediate and then I issue the load in compDidMount and render the appropriate UI in render (loading, showing cached data etc).

I agree, I't make the target component use the alias in its ident + :route-segment ["user" :user-alias] and model it as an entity with a single field, {:user-alias/data <data>} . . Then use perhaps a post-load mutation to move the user data into -> client-db :user/id <id> and replace its origin with an ident: -> client-db :user/alias <alias> :user-alias/data = [:user/id <id>]

Thanks for the suggestions! I also like the first suggestion with the component having the alias as an ident, since it plays along nicely with the routing out-of-the box. However, when if I instead have a pair of attributes which together indentify an entity, say a GitHub inspired example with username and repo name combination /user/andreas/repo/hello-world this solution doesn’t seem optimal since one’s need to create a ident with :user/alias+repo-name and make the server understand that. Also, that leaves a lot of duplicate aliases and the like all over the state.

I do not really see the difference between [:user/alias "andreas"] and [:git/repo ["my user" "my repo"]]

That’s true, I didn’t think of using vectors as ids, I’ll give that a shoot!

@U0CSAHDV0 ring any bells? Did we do something to GR with respect to highlight?

it does not…

@U07KXN95L possibly expound version???

This https://github.com/hhucn/decide3/blob/5e2819cde6ce524fcf2f0151204aac711fb3172f/src/main/decide/server_components/middleware.clj#L102 might be the answer I'm looking for

Right. The initial state is typically the tree generated from get initial on Root, with any addl stuff you might want to throw in.

For completeness, here's what I have and it appears to be working:

(defn- compute-context
  [request target]
  (let [session-state (merge (parsers/sessions-endpoint (get-query sessions/Session)
                                                        {:target [:component/id :session]
                                                         :remote :sessions
                                                         :request request})
                             {:session/next-uri (:uri request)})
        session-ident (get-ident sessions/Session session-state)
        server-side-state (-> (ssr/build-initial-state (get-initial-state ui/Root) ui/Root)
                              (assoc-in (conj [::dr/id ::ui/SiteRouter] ::dr/current-route)
                                        (get-initial-state target))
                              (set-query*
                                ui/SiteRouter {:query [::dr/id {::dr/current-route (get-query target)}]})
                              (assoc :sessions/session session-ident)
                              (assoc-in session-ident session-state))
        server-side-app (application/fulcro-app {:initial-db server-side-state})
        ;; TODO: Per ,
        ;; what is `normalized-db` and is it required? See also:
        ;; 
        server-side-props (denorm/db->tree (get-query ui/Root #_normalized-db) server-side-state server-side-state)
        content (binding [*app* server-side-app]
                  (dom/render-to-str (ui/ui-root server-side-props)))
        script-tag (ssr/initial-state->script-tag server-side-state)]
    {:content content
     :script-tag script-tag}))

On the client-side:

(defn ^:export init!
  []
  (let [initial-state (get-SSR-initial-state)]
    (reset! (::fapp/state-atom app) initial-state))
  (mount! app ui/Root "app" {:hydrate? true :intialize-state? false})
  (uism/begin! app sessions/state-machine :sessions/state-machine
               {:actor/session sessions/Session
                :actor/create-session sessions/SignIn})
  (hist/init! app)
  (messages/enable-messages!)
  (js/console.log "Fulcro app has been initialized"))

As Tony said, my problems in https://clojurians.slack.com/archives/C68M60S4F/p1617992612455400 do appear to be because initial state was incorrect

> and it appears to be working Sorry, my mistake. Works for some routes, not others.

normalized-db is the same thing as state-map

sorry for the confusion

Cool. Thanks for the clarification @U0CKQ19AQ

standard React fare there…nothing really to do with Fulcro (react-factory just passes along your stuff to React). Not sure how refs work in Native land

Thank you Tony