Clojure library for fast JSON encoding and decoding.
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README.md

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jsonissa / jsonista / jsoniin, jsonilla / jsonilta / jsonille

Clojure library for fast JSON encoding and decoding.

Much faster than Cheshire while still having all the necessary features for web development. Designed for use with Muuntaja.

Blogged:

Latest version

Clojars Project

Requires Java1.8+

Quickstart

(require '[jsonista.core :as j])

(j/write-value-as-string {"hello" 1})
;; => "{\"hello\":1}"

(j/read-value *1)
;; => {"hello" 1}

Examples

Changing how map keys are encoded & decoded:

(defn reverse-string [s] (apply str (reverse s)))

(def mapper
  (j/object-mapper
    {:encode-key-fn (comp reverse-string name)
     :decode-key-fn (comp keyword reverse-string)}))

(-> {:kikka "kukka"}
    (doto prn)
    (j/write-value-as-string mapper)
    (doto prn)
    (j/read-value mapper)
    (prn))
; {:kikka "kukka"}
; "{\"akkik\":\"kukka\"}"
; {:kikka "kukka"}

Reading & writing directly into a file:

(def file (java.io.File. "hello.json"))

(j/write-value file {"hello" "world"})

(slurp file)
;; => "{\"hello\":\"world\"}"

(j/read-value file)
;; => {"hello" "world"}

Adding support for joda-time Classes, used by clj-time.

;; [com.fasterxml.jackson.datatype/jackson-datatype-joda "2.9.5"]
(import '[com.fasterxml.jackson.datatype.joda JodaModule])
(import '[org.joda.time LocalDate])

(def mapper
  (j/object-mapper
    {:modules [(JodaModule.)]}))

(j/write-value-as-string (LocalDate. 0) mapper)
; "\"1970-01-01\""

Performance

  • All standard encoders and decoders are written in Java
  • Protocol dispatch with read-value & write-value
  • Jackson ObjectMapper is used directly
  • Small functions to support JVM Inlining

See perf-tests for details.

encode

decode

License

Copyright © 2016-2018 Metosin Oy.

Distributed under the Eclipse Public License 2.0.