Retract add Datahike example

retract-add-example.clj

(require '[datahike.api :as d])

(def schema [{:db/ident       :name
              :db/cardinality :db.cardinality/one
              :db/index       true
              :db/unique      :db.unique/identity
              :db/valueType   :db.type/string}
             {:db/ident       :sibling
              :db/cardinality :db.cardinality/many
              :db/valueType   :db.type/ref}
             {:db/ident       :age
              :db/cardinality :db.cardinality/one
              :db/valueType   :db.type/long}])

(def cfg {:store  {:backend :mem :id "sandbox"}
          :keep-history? true
          :schema-flexibility :write
          :initial-tx schema})

(d/delete-database cfg)

(d/create-database cfg)

(def conn (d/connect cfg))

(d/transact conn [{:name "Alice"
                   :age  25}
                  {:name "Bob"
                   :age  35}
                  {:name    "Charlie"
                   :age     45
                   :sibling [[:name "Alice"] [:name "Bob"]]}])

(d/q '[:find ?e ?n ?sn
       :where
       [?e :name ?n]
       [?e :sibling ?s]
       [?s :name ?sn]]
     @conn)

(d/transact conn {:tx-data [[:db/retract [:name "Charlie"] :sibling]
                            [:db/add [:name "Charlie"] :sibling [:name "Alice"]]]})

(d/q '[:find ?e ?n ?sn
       :where
       [?e :name ?n]
       [?e :sibling ?s]
       [?s :name ?sn]]
     @conn)