usage.md

Dation Usage

Configuring your schema

Your schema expects the following properties:

• name: keyword identifier for the schema, used to track this specific schema's changes.
• installs: vector of schema attributes to install.

Declaring Attributes

• Similar to Datomic, all schema reader literals are namespaced with db.
• Datomic value types (e.g. db.type/string) are not shortened so as to not sacrifice semantic meaning.

List of available reader literals:

db/attr

Generic attribute shorthand.

Expects vector of: [ident ?doc constraints ?pred]

The attributes ident keyword is always required, hence why its first.

An attributes constraints is a positional vector of built-in Datomic checks: [type cardinality (?unique | ?isComponent)].

As the last argument you can optionally pass an attribute's predicate symbol(s).

Examples:

#db/attr [:user/email [:db.type/string :db.cardinality/one :db.unique/identity]]
;; {:db/ident       :user/username
;;  :db/valueType   :db.type/string
;;  :db/cardinality :db.cardinality/one
;;  :db/unique      :db.unique/identity}

#db/attr [:user/username "Unique email for a user."
          [:db.type/string :db.cardinality/one :db.unique/identity]
          db.fns.attr-preds/email?]
;; {:db/ident       :user/email
;;  :db/doc         "Unique email for a user."
;;  :db/valueType   :db.type/string
;;  :db/cardinality :db.cardinality/one
;;  :db/unique      :db.unique/identity
;;  :db.attr/preds 'db.fns.attr-preds/email?}

db/spec

Entity spec attribute shorthand.

Expects vector of following format: [ident req-attrs ?pred].

Require attributes req-attrs is a vector of attributes that must be present in transaction.

Predicate pred is a symbol referencing an entity's predicate function.

#db/spec [:doc.spec/owner-fk [:doc/owner] 'myapp.doc.preds/owner?]
;; {:db.ident :doc.spec/owner-fk
;;  :db.entity/attrs [:doc/owner]
;;  :db.entity/preds 'myapp.doc.preds/owner?}