CODEWITHSUNDEEP
clojuredatomic
mia-wallace
mia-wallace

Reputation: 145

or clause in datomic

I am working with or clause in datomic. I know that using or in this query I get the users with :user/first-name "Mia" and users with :user/first-name "Wallace".

(d/q
  '[:find ?u
    :where
    (or [?u :user/first-name "Mia"]
        [?u :user/last-name "Wallace"])]
  (d/db conn))

But I would like a clause that works like Clojure's or. That's it, I want users with :user/first-name "Mia" and if there is not, I want to find the ones with :user/last-name "Lucas". Is it possible to do that in one query? I know that I can do it with two queries.

Upvotes: 1

Views: 339

Answers (1)

Alan Thompson
Alan Thompson

Reputation: 29958

You can do that using either a Collection Binding or a Relation Binding. From the docs:

A collection binding binds a single variable to multiple values passed in as a collection. This can be used to ask "or" questions, i.e. what releases are associated with either Paul McCartney or George Harrison?

;; query
[:find ?release-name
 :in $ [?artist-name ...]
 :where [?artist :artist/name ?artist-name]
        [?release :release/artists ?artist]
        [?release :release/name ?release-name]]

;; inputs
db, ["Paul McCartney" "George Harrison"]

;; result
#{["My Sweet Lord"] 
  ["Electronic Sound"]
  ["Give Me Love (Give Me Peace on Earth)"] 
  ["All Things Must Pass"]
  ...}

Upvotes: 2

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