Question

是否可以在datomic中为属性添加多个枚举？类似的东西：

[{:artist/name "Leonard Cohen"
  :artist/countries  [:country/GR :country/CA] }

在这种情况下，我会得到类似的东西＆＃34;：db.error / not-an-attribute：country / GR不是属性＆＃34;

然而

[{:artist/name "Leonard Cohen"
  :artist/countries  :country/GR  }

会起作用

Answer 1

请参阅the James Bond example in the Tupelo-Datomic library。简而言之，当添加多个enum属性时，您需要将它们包装在一个集合而不是向量中：

; Create some antagonists and load them into the db.  We can specify some of the
; attribute-value pairs at the time of creation, and add others later. Note that
; whenever we are adding multiple values for an attribute in a single step (e.g.
; :weapon/type), we must wrap all of the values in a set. Note that the set
; implies there can never be duplicate weapons for any one person.  As before,
; we immediately commit the new entities into the DB.
(td/transact *conn*
  (td/new-entity { :person/name "James Bond" :location "London"     :weapon/type #{ :weapon/gun :weapon/wit   } } )
  (td/new-entity { :person/name "M"          :location "London"     :weapon/type #{ :weapon/gun :weapon/guile } } )
  (td/new-entity { :person/name "Dr No"      :location "Caribbean"  :weapon/type    :weapon/gun                 } ))

数据库中的多个枚举

1 个答案: