Datascript101-Chapter1.clj

(ns dt.core
  (:require [datascript.core :as d]))

;; schema so nice
(def schema {:car/maker {:db/type :db.type/ref}
             :car/colors {:db/cardinality :db.cardinality/many}})

;; create the connection
(def conn (d/create-conn schema))

;; insert a maker
(d/transact! conn [{:maker/name "Honda"
                    :maker/country "Japan"}])

;; insert a maker a car along with it, referring back to
(d/transact! conn [{:db/id -1
                    :maker/name "BMW"
                    :maker/country "Germany"}
                   {:car/maker -1
                    :car/name "i525"
                    :car/colors ["red" "green" "blue"]}])

;; query a single the name of the cars we know for maker BMW.
(d/q '[:find ?name
       :where
       [?e :maker/name "BMW"]
       [?c :car/maker ?e]
       [?c :car/name ?name]]
     @conn)

;; Another way of doing this
(let [car-entity (ffirst
                  (d/q '[:find ?c
                         :where
                         [?e :maker/name "BMW"]
                         [?c :car/maker ?e]]
                       @conn))]
  (:car/name (d/entity @conn car-entity)))

Wuuuf, could you please please add an example in JS too? Thanks!

Wuuuf, could you please please add an example in JS too? Thanks!

Thank you for writing the Datascript 101 tutorial and giving newcomers like me a non-daunting way to get into it. Much appreciated!

Thank you for writing the Datascript 101 tutorial and giving newcomers like me a non-daunting way to get into it. Much appreciated!