Query doesn't work under advanced optimizations

[lilactown]

       (ds/q '[:find ?tx ?id ?v ?ts
               :where
               [?e :entry/value ?v ?tx]
               [?e :entry/id ?id ?tx]
               [?e :entry/ts ?ts ?tx]]
             app-db)

☝️ this query doesn't work under advanced optimizations. any ideas why?

#datascript/DB {:schema nil, :datoms [[1 :entry/id 15 536870914] [1 :entry/ts 1557849697260 536870914] [1 :entry/value {:value 1, :meta nil} 536870914]]}

is the DB for instance and that query returns #{[nil nil nil nil]}

[tonsky]

Works for me on

[org.clojure/clojure       "1.10.0"]
[org.clojure/clojurescript "1.10.520"]

what version of compiler are you on?

[lilactown]

This was due to missing externs while using shadow-cljs. thheller pointed me to #216; adding :externs ["datascript/externs.js"] to :compiler-options map in my shadow-cljs.edn fixed the issue for now.

Is there some place we can note this, if we can't remove the need for externs to be present under advanced optimizations?

[tonsky]

Well the idea of externs is that they are absolutely required. Why else have them?

[lilactown]

I'm not sure I understand. My point was that I had no idea that adding the externs to my project config was necessary. I was thinking that we could add a note to the installation instructions.

[tonsky]

Totally! shadow-cljs README should mention this for all CLJS projects!

[jamesnyika]

Confirming as well that this query

(d/q '[:find [?e ...]
         :in $ ?attribute
         :where
          ;[?e :event/name] ;; I USED TO HAVE TO DO THIS
          [?e ?attribute]  ;; BUT NOW I CAN INSTEAD DO THIS
          [?e :event/active true]] ds attribute))

WORKS just by adding this to my shadow-cljs.edn file

...
 :compiler-options {:infer-externs :auto
                      :externs ["datascript/externs.js"]} ;; <--- just add this in

[jamesnyika]

I added a section under the wiki Tips & Tricks section.

[yqrashawn]

Hi,

I followed this issue and add those two :compiler-options to shadow-cljs config and found a datascript is not defined error.
It turns out the compiled prod.js defines datascript with datascript={} instead of var datascript={}.

Since my build target is :esm, having datascript={} kind of expression will cause the datascript is not defined error.

My solution is to add :prepend-js "if(window)window.datascript={};" to shadow-cljs.edn like bellow.

{:target :esm
 ...
 :compiler-options {:infer-externs :auto
                    :externs ["datascript/externs.js"]}
 :modules {:app {:exports ...
                 :prepend-js "if(window)window.datascript={};"}

Just put it here in case someone encounters the same problem.

[tonsky]

@yqrashawn I am not familiar with how shadow processes externs. Does it simply prepends them? Do you think externs bundled with DataScript should be changed (e.g. datascript -> global.datascript?)

[yqrashawn]

I'm not familiar with closure compiler. I tried this in externs.js file. It's not work. Closure compiler still compiles it to ;datascript={} in the outmost scope of a ESM js file.

I guess closure compiler don't know about that user is going to use the file in as a ESM file, only shadow-cljs knows about it.

if (global) global.datascript = datascript
else if (window) window.datascript = datascript
else {
  var datascript = {}
}

[logseq-cldwalker]

@yqrashawn Thanks for the snippet. I wasn't able to use it in :prepend-js as I get this error - https://github.com/google/closure-compiler/wiki/FAQ#i-got-a-partial-alias-created-for-namespace-error--what-do-i-do . I was able to use your snippet with :prepend e.g.:

:prepend "if (global) { global.datascript = datascript } else if (window) { window.datascript = datascript } else { var datascript = {}}"