Datalog variables are only found and understood in the first level of the expression. Your form has it nested

Hi @U09R86PA4, thank you. Do you have any ideas how I might be able to get the result I'm after? I'm not stuck with this approach, but I need a way to filter on dates at query time. In this example each data-source will have a different frequency and that would cause things to go stale at different times, so I can't hardcode the date to check against

Keeping the same approach you can split the expressions up

I'm sorry, I'm not sure how I would do that. Could you show me a short example? Do bind each part like (.minus ?now (java.time.Duration/ofMillis ?freq)) somehow? I tried this is this what you mean?

(let [query '[:find (pull ?e [:*])
                :in $ ?now
                :where
                [?e :data-source/uri]
                [?e :schedule/interval-millis ?freq]
                [?e :data-source/history ?h]
                [?h :event/instant ?i]
                [?my-freq _ (java.time.Duration/ofMillis ?freq)]
                [?my-something _ (.minus ?now ?freq)]
                [(> ?i ?my-something)]]
        db (d/db (resolver/get-db-connection))]
    (d/q query db (time-utils/now)))

Yeah not sure if that does anything @U09R86PA4, I think you must mean something else

Ah I think I got it:

(let [query '[:find ?elapsed
                :in $ ?now
                :where
                [?e :data-source/uri]
                [?e :schedule/interval-millis ?freq]
                [?e :data-source/history ?h]
                [?h :event/instant ?i]
                [(com.sajb.time-utils.interface/duration-between ?i ?now) ?elapsed] 
                [(> ?elapsed ?freq)]]
        db (d/db (resolver/get-db-connection))]
    (d/q query db (time-utils/now)))

Works! Thank you @U09R86PA4

https://github.com/Datomic/day-of-datomic/blob/20c02d26fd2a12481903dd5347589456c74f8eeb/tutorial/query.clj#L138

Yeah you got it. I just meant something like this (I assume ?now is java.time.Instant and :event/instant is :db.type/instant/`java.util.Date` from your code):

[?e :schedule/interval-millis ?freq]
[(.minusMillis ^java.time.Instant ?now ?freq) ?threshold-inst]
[(java.util.Date/from ?threshold-inst) ?threshold]
[?e :data-source/history ?h]
[?h :event/instant ?i]
[(< ?i ?threshold)]

Notice all the function expressions have datalog variables on the outer list only

You have to bind all the intermediate values, or do the work in a function

Got it. Do you think it's better to use built in java methods over custom clojure functions?

is there a difference when it comes time to deploy?

are you using on-prem or cloud?

going to use cloud

yes, you need to include them in the ion and allow-list them: https://docs.datomic.com/cloud/query/query-data-reference.html#deploying

for on-prem you don’t need to do anything--the query executes in the same process as the querying code, so the function is already available.

Got it, thanks so much for all the help

If your goal is to expose the results of datomic queries/tx results to HTTP clients then you will need to write a web service whose entry point is the :http-direct value in your ion-config.edn file. It's not hard, but it certainly introduces a much bigger design space than just handling lambda requests. (I'm not certain I really understood your question, so please add some more details if you think I missed the target here).

Hey, my main question is focusing on the response payload format, I am already using the lambdas to query/tx (not by http-direct). I want to turn the Datomic responses into JSON, so I would be able to read it from my python service (the response from the lambda). I have already tried using some libs for writing the Datomic results into string, but transact results for example, contains some clojure features like tags such as #datom which I can’t parse: tx response: [#datom[13194139533423 50 #inst "2024-02-05T09:15:16.762-00:00" 13194139533423 true]] how can I turn this to JSON? Thanks 🙏

In Cloud (and probably on-prem) datoms can be thought of as 5-tuples that can be access sequentially (IIRC) and associatively with :e, :a, :v, :tx and :added. That's all the information content of a datom AFAIK. So you could easily write something that turns each datom into an array or map and further into JSON. You'll probably face a similar problem with the :db-after and :db-before values. There, I think the valuable information content is the "t" value and if you are already presenting the datoms then the t value is somewhat less useful since it can be derived from the tx of the datoms. But you could convey it to your callers as well.

A little more on the problem: I'm creating a little testing client just so I could connect it to datomic. The code base has just these lines of code:

(ns client.core
 (:require [client.env :as env]
           [datomic.client.api :as d]))

(def cfg {:server-type :cloud
          :region "as-east-1" ;; e.g. us-east-1
          :system "nu-futuro-cache-rod"
          :creds-profile "nufuturo"
          :endpoint ""})

(def client (d/client cfg))
(d/create-database client {:db-name "movies"})

Would love to help but I'm not there yet myself. Hopefully someone chimes in soon

as-east-1 vs sa-east-1

Nice catch @U0698L2BU

Omg, thank you! It worked ❤️