datomic/schema について
必須の schema 項目
db/ident
db/ident は必須の値。 hoge.fuga/piyo のように書ける。hoge.fuga は namespace で、 db は予約されている。
db/valueType
db/valueType も必須。keyword で指定される。 以下の属性から選ぶ。
{% blockquote %} :db.type/keyword - Value type for keywords. Keywords are used as names, and are interned for efficiency. Keywords map to the native interned-name type in languages that support them.
:db.type/string - Value type for strings.
:db.type/boolean - Boolean value type.
:db.type/long - Fixed integer value type. Same semantics as a Java long: 64 bits wide, two's complement binary representation.
:db.type/bigint - Value type for arbitrary precision integers. Maps to java.math.BigInteger on Java platforms.
:db.type/float - Floating point value type. Same semantics as a Java float: single-precision 32-bit IEEE 754 floating point.
:db.type/double - Floating point value type. Same semantics as a Java double: double-precision 64-bit IEEE 754 floating point.
:db.type/bigdec - Value type for arbitrary precision floating point numbers. Maps to java.math.BigDecimal on Java platforms.
:db.type/ref - Value type for references. All references from one entity to another are through attributes with this value type.
:db.type/instant - Value type for instants in time. Stored internally as a number of milliseconds since midnight, January 1, 1970 UTC. Maps to java.util.Date on Java platforms.
:db.type/uuid - Value type for UUIDs. Maps to java.util.UUID on Java platforms.
:db.type/uri - Value type for URIs. Maps to java.net.URI on Java platforms.
:db.type/bytes - Value type for small binary data. Maps to byte array on Java platforms. {% endblockquote %}
db/cardinality
カーディナリティ。1 か N かを表現する。
{% blockquote %} :db.cardinality/one - the attribute is single valued, it associates a single value with an entity
:db.cardinality/many - the attribute is multi valued, it associates a set of values with an entity
Transactions can add or retract individual values for multi-valued attributes.
{% endblockquote %}
オプションの schema 項目について
{% blockquote %} :db/doc specifies a documentation string. :db/unique - specifies a uniqueness constraint for the values of an attribute. Setting an attribute :db/unique also implies :db/index. The values allowed for :db/unique are: :db.unique/value - the attribute value is unique to each entity; attempts to insert a duplicate value for a different entity id will fail :db.unique/identity - the attribute value is unique to each entity and "upsert" is enabled; attempts to insert a duplicate value for a temporary entity id will cause all attributes associated with that temporary id to be merged with the entity already in the database. :db/unique defaults to nil. :db/index specifies a boolean value indicating that an index should be generated for this attribute. Defaults to false. :db/fulltext specifies a boolean value indicating that an eventually consistent fulltext search index should be generated for the attribute. Defaults to false. :db/isComponent specifies that an attribute whose type is :db.type/ref refers to a subcomponent of the entity to which the attribute is applied. When you retract an entity with :db.fn/retractEntity, all subcomponents are also retracted. When you touch an entity, all its subcomponent entities are touched recursively. Defaults to nil. :db/noHistory specifies a boolean value indicating whether past values of an attribute should not be retained. Defaults to false. {% endblockquote %}
スキーマ定義
{% blockquote %} {:db/id #db/id[:db.part/db] :db/ident :person/name :db/valueType :db.type/string :db/cardinality :db.cardinality/one :db/doc "A person's name" :db.install/_attribute :db.part/db} {% endblockquote %} db.install の _attribute の _ は 逆方向の参照を使っていて、 db.part/db から 新しい参照への参照を作る？らしい。 day-of-datomic の例でも全部:db.install/_attribute :db.part/db だったので、今のところ決め打ちでもいいかもしれない。
パーティション
についても書かれているが、様々なサンプルみても使ってないのでスルー。
(def db (d/db conn)) (d/q '[:find ?ident :where [_ :db/ident ?ident]] db)
実際にやってみる
データの追加
(defn dbschema [] [(s/schema user (fields [username :string :indexed] [pwd :string "Hashed password string"] [email :string :indexed] [status :enum [:pending :active :inactive :cancelled]] [group :ref :many]))
(s/schema group (fields [name :string] [permission :string :many]))])
insert 成功
(d/transact (d/connect db-url) [{:db/id #db/id[:db.part/user] :user/username "vimtaku" :user/pwd "hogeFuga1" :user/email "vimtaku@gmail.com" :user/status :user.status/pending } ])
(d/q '[:find ?e :where [?e :user/username] ] db)
(d/q '[:find ?c :where [?c :user/pwd]] db)
(d/transact (d/connect db-url) [{:db/id #db/id[:db.part/user] :user/username "vimtaku" :user/pwd "hogeFuga2" :user/email "vimtaku@gmail.com" :user/status :user.status/pending } ])
(defn vimtaku [] (def q-result (d/q '[:find ?e ?u ?p ?em ?s :in $ ?name :where [?e :user/username ?name] [?e :user/username ?u] [?e :user/pwd ?p] [?e :user/email ?em] [?b :user/status ?_s] [?_s :db/ident ?s] ] (d/db (d/connect db-url)) "vimtaku2")) q-result )
(def ent (d/entity dbval (ffirst q-result)))
(d/transact (d/connect db-url) [{:db/id #db/id[:db.part/user] :user/username "vimtaku" :user/status :user.status/active } ]) これで upsert される.
(defn lookup [un] (def q-result (d/q '[:find ?e ?u ?p ?em ?s :where [?e :user/username ~un] [?e :user/username ?u] [?e :user/pwd ?p] [?e :user/email ?em] [?b :user/status ?_s] [?_s :db/ident ?s] ] (d/db (d/connect db-url)))) q-result )
(defn lookup [un] (def q-result (d/q '[:find ?name ?p ?em ?s :in $ ?name :where [?e :user/username ?name] [?e :user/pwd ?p] [?e :user/email ?em] [?b :user/status ?_s] [?_s :db/ident ?s] ] (d/db (d/connect db-url)) un)) q-result )