Unusual syntax JSON parse problem String (Clojure)

Question

I have a long clojure String (java.lang.String) representing a JSON. It has "normal" looking syntax like so:

"{ a:1, b:"hello" }"

The keys do not have quotes around them.

All the libraries I have looked at such as clojure.data.json want this syntax in order to parse into an object:

"{\"a\":1,\"b\":"hello"}"

Is there a way to parse the top syntax into json or clj objects? Any help is appreciated. Thank you.

This isn't a solution for clojure, per se, so not a duplicate, but might give you some ideas: stackoverflow.com/questions/2060356/… — jas
– jas, Commented Feb 25, 2019 at 19:41
This is not valid JSON, but a JavaScript object. You'll notice when you try it in a validator like jsonlint.com. — Michiel Borkent
– Michiel Borkent, Commented Feb 25, 2019 at 19:53
The unfortunate answer is you'll have to parse it yourself. The only (better) answer is to get the source to feed you valid JSON instead. — Jared Smith
– Jared Smith, Commented Feb 25, 2019 at 20:35

cfrick · Accepted Answer · 2019-02-25 21:49:37Z

4

Depending on your level of desperation, the Groovy JSON Slurper can read this "JSON" in the LAX setting (which allows those attributes, comments, ...)

Add the following dep:

[org.codehaus.groovy/groovy-json "2.5.6"]

Then you can run:

user=> (import [groovy.json JsonSlurper JsonParserType])
groovy.json.JsonParserType
user=> (def parser (doto (JsonSlurper.) (.setType JsonParserType/LAX)))
#'user/parser
user=> (def data (.parseText parser "{ a:1, b:\"hello\" }"))
#'user/data
user=> data
{"a" 1, "b" "hello"}

answered Feb 25, 2019 at 21:49

cfrick

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2 Comments

Alan Thompson Over a year ago

Nice! I didn't know that was available from Clojure.

cfrick Over a year ago

It's just .class files in a jar... :)

Alan Thompson · Accepted Answer · 2019-03-22 06:05:56Z

Update 2019-3-21

The link from @jas includes a comment that "it looks like YAML" (if the colons are followed by a space).

I have integrated the new snakeyaml-engine library into the Tupelo Library. API docs are here. The answer is now super-simple:

(ns tst.demo.core
  (:use demo.core tupelo.core tupelo.test)
  (:require [tupelo.parse.yaml :as yaml] ))

(dotest
  (let [data-1 "{ a: 1, b: 'Hello World' }"]
    (is= (yaml/parse data-1) {:a 1, :b "Hello World"})))

Old Answer

Given project.clj

 [io.forward/yaml "1.0.9"]

this works:

(ns tst.demo.core
  (:require [yaml.core :as yaml]) )

(def data-1 "{ a: 1, b: \"Hello World\" }" )

  (let [result-raw (yaml/parse-string data-1)
        result     (into {} result-raw)]

with result

----------------------------------
   Clojure 1.10.0    Java 10.0.1
----------------------------------

Testing tst.demo.core
result-raw   => #ordered/map ([:a 1] [:b "Hello World"])
result       => {:a 1, :b "Hello World"}

Unfortunately it (currently) fails under Java 11 because a dependent library needs a type hint. You can work around this by fixing up your project.clj:

  :dependencies [
     [io.forward/yaml "1.0.9" :exclusions [org.flatland/ordered
                                           org.yaml/snakeyaml] ]
     [org.yaml/snakeyaml "1.23"]
     [org.flatland/ordered "1.5.7"]
     [org.clojure/clojure "1.10.0"]

I filed an issue with the io.forward/yaml project to update their dependencies.

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