Transit

Web Development with Clojure, Third Edition — by Dmitri Sotnikov, Scot Brown (95 / 107)

👈 EDN | TOC | Appendix 4 Database Access 👉

Transit has feature parity with EDN but has some slight quirks because it’s more optimized and it’s more commonly used across different environments. Most notably, the default tags are different from EDN.

Here’s an example of a reader/writer pair for a LocalDate type in Clojure taken from luminus-transit.[103]

​ ​;; In Clojure​
​ (​require​ '[cognitect.transit :as transit])
​ (import '[java.time LocalDate]
​         '[java.io ByteArrayInputStream ByteArrayOutputStream]
​         '[java.time.format DateTimeFormatter])
​ 
​ (​def​ read-handlers {​"LocalDate"​
​                     (​transit/read-handler​
​                      #(​java.time.LocalDate/parse​ %
​                        (​DateTimeFormatter/ofPattern​ ​"yyyy-MM-dd"​)))})
​ (​def​ write-handlers
​   {java.time.LocalDate
​    (​transit/write-handler​
​     (constantly ​"LocalDate"​)
​     #(​.format​ % (​DateTimeFormatter/ofPattern​ ​"yyyy-MM-dd"​)))})
​ 
​ (​def​ out (​ByteArrayOutputStream.​ 4096))
​ 
​ (​transit/write​ (​transit/writer​ out :json {:handlers write-handlers})
​                (​LocalDate/of​ 2020 12 31))
​ 
​ (println (​.toString​ out))
​ ​;; => ["~#LocalDate", "2020-12-31"]​
​ 
​ (println
​   (​transit/read​
​     (​transit/reader​ (​ByteArrayInputStream.​ (​.toByteArray​ out))
​                     :json
​…