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PONesting structures With Datomic
 

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    <p>Using Datomic, I'm trying to think of how can I nest a list within a list? </p> <p>An example Clojure data structure would be something (see <em>fig.1</em>). I know that Datomic has the notion of references (ex. in <em>fig.2</em>). But those just look like scalar types, not objects (per se). </p> <pre><code> [{:id 0, :symbol DDD, :company 3D Systems Corporation, :price-difference 1.3100000000000023, :event-list [{high 35.11, tickerId 0, WAP 34.491, open 35.07, date 20130426, count 3403, low 33.8, hasGaps false, close 34.53, field historicalData, volume 8667, type historicalData}]}] </code></pre> <p><em><strong>fig.1</em></strong></p> <pre><code> {:db/id #db/id[:db.part/db] :db/ident :district/region :db/valueType :db.type/ref :db/cardinality :db.cardinality/one :db/doc "A district region enum value" :db.install/_attribute :db.part/db} ;; district/region enum values [:db/add #db/id[:db.part/user] :db/ident :region/n] [:db/add #db/id[:db.part/user] :db/ident :region/ne] [:db/add #db/id[:db.part/user] :db/ident :region/e] [:db/add #db/id[:db.part/user] :db/ident :region/se] [:db/add #db/id[:db.part/user] :db/ident :region/s] [:db/add #db/id[:db.part/user] :db/ident :region/sw] [:db/add #db/id[:db.part/user] :db/ident :region/w] [:db/add #db/id[:db.part/user] :db/ident :region/nw] </code></pre> <p><em><strong>fig.2</em></strong></p> <p>[EDIT]</p> <p>Actually, I think I might have found the answer <a href="https://github.com/Datomic/day-of-datomic/blob/master/resources/day-of-datomic/schema.edn#L36">here</a>. I was going through the <a href="https://github.com/Datomic/day-of-datomic">Day-Of-Datomic</a> code base, and found the example below. But I'm still not clear on what explicitly ties the <strong><em>:comments</em></strong> namespace to the <strong><em>:comment/body</em></strong> (or <strong><em>:comment/author</em></strong>) namespace(s). Does Datomic just use convention to link <strong><em>:comments</em></strong> to <strong><em>:comment</em></strong> ? </p> <pre><code> ;; comments [{:db/id #db/id[:db.part/db] :db/ident :comments :db/valueType :db.type/ref :db/cardinality :db.cardinality/many :db/isComponent true :db.install/_attribute :db.part/db} {:db/id #db/id[:db.part/db] :db/ident :comment/body :db/valueType :db.type/string :db/cardinality :db.cardinality/one :db.install/_attribute :db.part/db} {:db/id #db/id[:db.part/db] :db/ident :comment/author :db/valueType :db.type/ref :db/cardinality :db.cardinality/one :db.install/_attribute :db.part/db}] </code></pre> <p><em><strong>fig.1</em></strong> </p>
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    1. CONothing ties :comments and :comment/body. It's just a naming convention. For an example of how to persist a list of lists, see my answer below. I used two random attribute definitions to persist the equivalent of [["a" "b" "c"]["d" "e" "f"]] in Clojure.
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