Ok I get this part now, so the whole reason for -fx handlers is to keep event (effect) handling function pure and somehow by some magic, I am given the stuff that I need from the outside world in the cofx map.

So before my handler is ran, re-frame needs to fetch the coeffects that I am interested in, so I need to tell re-frame which are this coeffects, right ?

Oh, I need to read on :face_with_rolling_eyes:

@gadfly361 @geoffs @mikethompson Thanks guys. I’ll think about it.

@smnplk sounds like you are on the right track

I cant figure out what the signature for a reg-sub-raw Layer 3 intermediate-node should look like; would it be something like

(reg-sub-raw (register-handler ...) (register-handler ...))

@owen why do you need reg-sub-raw ?

@owen usage:

(reg-sub-raw  
   :an-id 
   some-fn)

(defn some-fn 
   [app-db event]        ;; app-db is a r/atom not a value
   .... returns a reaction ...)

can I return reactions from reg-sub?

I want to use :on-dispose

I was assuming reg-sub-raw is the way to return a reaction

@mikethompson right, but with the intermdiate subscriptions

its like:

(reg-sub (fn ...) (fn ...))

reg-sub-raw takes a different arg signature

yep, see above

alright lemme mull on this

Reading list ... To understand reactions and r/atom interplay: https://github.com/Day8/re-frame/blob/master/docs/SubscriptionFlow.md The old README (the old name for reg-sub-raw was register-sub) https://github.com/Day8/re-frame/blob/6f56b72fd0f72f1d744a0406256d753e0c9715b1/README.md#the-signal-graph Example of use (including on-dispose) https://github.com/Day8/re-frame/blob/develop/docs/Subscribing-To-External-Data.md

@owen ^^

right, the subscribe to external data sources is where I learned of :on-dispose

its only because this would be an intermediate subscription that I'm not sure what the signature would look like

would I need to drop down to register-handler for this?

No, register-handler is the old name for registering event handlers

Here. we are in the world of subscription handlers

its still in

https://github.com/Day8/re-frame/blob/master/src/re_frame/subs.cljc

Does this help: https://clojurians.slack.com/archives/re-frame/p1482864202002619

If you want to use :on-dispose ... then you are going to be doing somethng like this:

(reg-sub-raw 
   :some-id
   (fn [app-db event]
       ...... return some reaction in here which has an :on-dispose)

Then that can be used like this (subscribe [:some-id])

Which is standard

right but unless I'm mistaken the some-fn is providing the first argument of app-db which wouldnt work in intermidiate subscriptions

ala https://github.com/Day8/re-frame/blob/master/examples/todomvc/src/todomvc/subs.cljs#L82

instead of app-db its your query-vector

and then the second fn takes the dynamic vector: (fn [[todos showing] _]

I guess what Im trying to achieve is

(reg-sub-raw
  :id: 
  (fn [query-v _]
    [vector of subscriptions])
  (fn [[subscriptions] _]
    (make-reaction
      :on-dispose)))

but the 3rd argument doesnt fit reg-sub-raw's signature

(reg-sub-raw 
   :some-id 
   (fn [app-db event]
      (make-reaction 
          (fn []  
                use  @app-db or @(subscribe [:some-other] ....)
           :on-dispose  (fn [] ...))))

In effect you just use subscribe [:stuff] within the reaction

(being sure to put a @ on the front

@owen ^^

So with reg-sub-raw you do not define the input signals, like reg-sub you just use straight subscriptions within the returned reaction

being sure to put @ on the front <--- forgetting this is a trap for newbies everytime

ok I think the > with reg-sub-raw you do not define the input signals, like reg-sub makes sense

if thats true and reg-sub-raw always takes app-db as an arg though

doesnt it re-compute everytime db is changed?

Yes, always

ah

so is it less efficient to use rsr or reg-sub?

Pretty much the same

ok cool

think I got it

thanks man

no problem

@owen updated docs https://github.com/Day8/re-frame/blob/develop/docs/SubscriptionFlow.md#reg-sub-raw

great timing! that new doc was exactly what I needed

yeah, that was the main reason why I’ve choosen reagent+re-frame over other projects: badass documentation.

A+ and agreed, docs are this libraries true silver bullet 🙂

My app is re-frame on client side. On server side, I need (1) persistence (kv store) and (2) passing messages between clients in real time. What server setup works nicely with cljs/re-frame on client side?

rethink db?

Didn't rethinkdb just shut down?

yes

I have no experience with couchdb, but I would look into it for something like this @qqq

rethinkdb, the commercial entity has closed, but it is likely that rethinkdb the OSS entity will continue on in some form (exact form unknown).

yep

@qqq have you considered firebase?

I seem to remember the clojurescript library is called matchbox

@mikethompson: would work well as I'm currently using GCP

I'd just like to use whatever fits nicely into the re-frame network, as I have complete power over what tech to use.

We used firebase and found it very quick to get going. The data model you get is very limited, and we eventually moved to rethinkdb (which we loved).

@mikethompson: are you using gcp, aws, digital ocean, or your own hosting; and is there a blog post on this somewhere?

rethinkdb was a lot more work

firebase is hosted

Which is part of the reason it is so easy to get going

For rethinkdb we used http://compose.io for hosting. Seems a bit too expensive, but we've never bothered to move away

I'm a little squeamish on using http://compose.io ; is there a way to get aws aurora or aws rds to provide the 'real time streaming' part?

Also, the mighty @yogthos has detailed how to do this with PostgreSQL: https://yogthos.net/posts/2016-11-05-LuminusPostgresNotifications.html

@mikethompson : that's what I want! notifications on DB modifications; thanks!

@frank @owen I changed the placement of those new reg-sub-raw docs to: https://github.com/Day8/re-frame/blob/develop/docs/SubscriptionFlow.md#reg-sub-raw