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datascript
seepel 2024-03-28T23:35:58.776619Z
I have a question, I read the datascript 2 blog post and I keep wondering about this
> Well, it surprised me as well that in 3 years of full-time web app development with DataScript I haven’t used a single query.
The place where I use queries is when I want to grab an eid that is on the other side of a :db.unique/identity attribute like this. I have a linked list of messages, and a main chat object that points to the last message in that history. I have the chat entity and I want to get the last message entity so I do this.
(defn last-chat-message [db chat-eid]
(d/q '[:find ?message .
:in $ ?chat
:where
[?chat :chat/last-message ?message]]
db chat-eid))
Niki 2024-03-30T18:03:54.046219Z
Looks like I added find-datom that replaces d/datoms + first
Niki 2024-03-30T18:04:06.085929Z
Still feels clumsy though
seepel 2024-03-30T18:09:59.360589Z
Ahhh, good idea. Something like this?
(defn find-datom [db idx & args]
(first (apply d/datoms db idx args)))
(defn find-ent [db idx & args]
(:e (apply find-datom db idx args)))
(defn find-attr [db idx & args]
(:a (apply find-datom db idx args)))
(defn find-value [db idx & args]
(:v (apply find-datom db idx args)))
(defn find-tx [db idx & args]
(:tx (apply find-datom db idx args)))Niki 2024-03-30T18:39:48.903679Z
Yeah, and find-datom is already in
Niki 2024-03-29T14:34:16.076259Z
(-> (d/datoms db :eavt chat-eid :chat/last-message)
first
:e)Niki 2024-03-29T14:34:26.222169Z
Basically query would do the same under the hood
Niki 2024-03-29T14:36:00.340749Z
But because of overhead on parsing/executing and being generic it takes more time doing the query
Niki 2024-03-29T14:36:16.022539Z
Maybe the fact that I know how it works affects my preference
🎯 2
seepel 2024-03-29T16:14:34.620259Z
Thanks! I have done it that way too, but both ways felt kind of wrong to me.