Clojurians Log v2

i've just started to use the client api recently (after a few years of dealing only with the peer api). when i tried to test something simple, i was getting this error:

Execution error (ExceptionInfo) at datomic.client.api.impl/incorrect (impl.clj:43).
Query args must include a database

(dc/q '[:find ?k ?v
        :where [(System/getProperties) [[?k ?v]]]])

(dc/q '[:find [?b]
        :in [?tup]
        :where [[(untuple ?tup) [?a ?b]]]]
      [1 2])

for the 1st case, where the :in clause is omitted, i might understand the error, but for the second case, i definitely don't expect it

client query must take a db, can’t be run against a collection the way peer query can

@onetom ^

so it's a "bug" in the documentation then, isn't it?

i can look at the docs, if they are client-specific docs then yes

the cloud docs - i linked - is all client api specific, no?

yes, that example should take a db

but now that we are talking about it, of course it needs a "db", since that's how the query itself can reach the query engine over the network...

right 🙂

i keep finding myself reaching for the peer api functions, like entid, ident etc. the https://docs.datomic.com/on-prem/clients-and-peers.html#peer-only section of the docs makes it clear that we should use the pull api instead of these functions, but that's just much more verbose. same issue with the lack of the find-coll and find-scalar from find-spec. is there any official or popular compatibility lib which fills this gap?

or is there any good examples how to sturcture an app in a way that it's concise to test?

for example, given this function:

(defn by-name
  [db merchant-name]
  (-> {:query '{:find  [?merchant]
                :in    [$ ?merchant-name]
                :where [(or [?merchant :merchant/name ?merchant-name]
                            [?merchant :merchant/name-en ?merchant-name])]}
       :args  [db merchant-name]}
      (dc/q)
      (ffirst)))

(deftest by-name-test
  (testing "exact match"
    (let [db (db-of [{:db/ident      :some-merchant
                      :merchant/name "<merchant name in any language>"}])]
      (is (match?
            (->> :some-merchant (dc/pull db [:db/id]) :db/id)
            (merchant/by-name db "<merchant name in any language>"))))))

the benefit of operating with idents is that the test failure messages are symbolic and i don't have to muck around with destructuring string temp-ids, potentially across multiple transactions

i can understand that the client api doesn't want to provide find-scalar and find-coll and ident, entid, so the interface size is small, which helps providing alternative implementations, like the dev-local one, but these functions are just too useful for REPL work and automated tests. i can also understand how they might seep into application code, promoting inefficient code, but that's not a strong reason for not providing them officially.

for now, i made a custom matcher, which results in tests like this:

(is (match?
      (idents-in db
                 :matching-merchant-1
                 :matching-merchant-2)
      (merchant/named-like db "matching")))

(ns ...
  (:require
    [matcher-combinators.core :refer [Matcher]] ...))

(defrecord MatchIdents [db expected-idents]
  Matcher
  (-matcher-for [this] this)
  (-matcher-for [this _] this)
  (-match [_this actual-entity-refs]
    (if-let [issue (#'matcher-combinators.core/validate-input
                     expected-idents
                     actual-entity-refs
                     sequential? 'in-any-order "sequential")]
      issue
      (#'matcher-combinators.core/match-any-order
        expected-idents
        (mapv (comp :db/ident (partial dc/pull db [:db/ident]))
              actual-entity-refs)
        false))))

(defn idents-in [db & entity-idents]
  (->MatchIdents db entity-idents))

I have an incident where datomic cloud started giving me busy indexing errors

I supposed I exceeded my node limit, the stop transacting entirely

but after 40min it still gives me busy indexing errors