Example that compares parsing a complex json object in go and in elixir

parse_complex_json.exs

# { "DocVersions": {
#     "1": {
#       "version_date": "2015-10-06 12:00:00",
#       "objects": [
#         { "LogicalObjNum":1,
#           "PhysicalObjNum":1,
#           "FileExtension":"TIF",
#           "FileFmtDesc":"TIFF Images (Black and White)"}
#       ]
#     }
#   },
#   "DocLabels":[ {"label":"ed"}, {"label":"Ann"}]
# }

json_string = "{ \"DocVersions\": { \"1\": { \"version_date\": \"2015-10-06 12:00:00\", \"objects\":[ { \"LogicalObjNum\":1, \"PhysicalObjNum\":1, \"FileExtension\":\"TIF\", \"FileFmtDesc\":\"TIFF Images (Black and White)\"} ] } }, \"DocLabels\":[{\"label\":\"Ed\"},{\"label\": \"Ann\"}]}"
meta = Poison.Parser.parse!(json_string)

[first_label | _] = Map.get meta, "DocLabels"
versions = Map.get meta, "DocVersions"

IO.puts "Label One: #{first_label["label"]}"
IO.puts "Versions:"

print_object = fn(o) ->
  Enum.map(o, fn {k, v} -> IO.puts "      #{k}: #{v}" end)
end

print_version = fn {k, v} ->
  IO.puts "  Version: #{k}"
  IO.puts "    Date:  #{v["version_date"]}"
  IO.puts "    Objects:"
  Enum.map(v["objects"], fn obj -> print_object.(obj) end)
end

Enum.map(versions, print_version)

parse_complex_json.go

package main

import (
	"encoding/json"
	"fmt"
)

func main() {
	/*
		   { "DocVersions": {
		   		"1": {
						"version_date": "2015-10-06 12:00:00",
						"objects":
							[{ "LogicalObjNum":1,
									"PhysicalObjNum":1,
									"FileExtension":"TIF",
									"FileFmtDesc":"TIFF Images (Black and White)"}
							]
						}
				},
				"DocLabels":[{"label":"Ed"}, {"label":"Ann"}]
		   }
	*/

	type Meta struct {
		DocVersions map[string]struct {
			Date    string `json:"version_date"`
			Objects []struct {
				LogicalObjNum  int
				PhysicalObjNum int
				FileExtension  string
				FileFmtDesc    string
			} `json:"objects"`
		}
		DocLabels []struct {
			Value string `json:"label"`
		}
	}

	var meta Meta

	jsonString := "{ \"DocVersions\": { \"1\": { \"version_date\": \"2015-10-06 12:00:00\", \"objects\":[ { \"LogicalObjNum\":1, \"PhysicalObjNum\":1, \"FileExtension\":\"TIF\", \"FileFmtDesc\":\"TIFF Images (Black and White)\"} ] } }, \"DocLabels\":[{\"label\":\"Ed\"},{\"label\": \"Ann\"}]}"
	jsonByteArray := []byte(jsonString)
	json.Unmarshal(jsonByteArray, &meta)
	fmt.Println("Label One:", meta.DocLabels[0].Value)
	fmt.Println("Versions:")
	for versionNum, version := range meta.DocVersions {
		fmt.Printf("  Version: %v %s\n", versionNum, version.Date)
		fmt.Println("    Objects: ")
		for _, object := range version.Objects {
			fmt.Printf("       Object %d, Page %d: %s - %s\n",
				object.PhysicalObjNum, object.LogicalObjNum, object.FileExtension, object.FileFmtDesc)
		}
	}
}

parse_complex_json.rb

require 'json'

# { "DocVersions": {
#     "1": {
#       "version_date": "2015-10-06 12:00:00",
#       "objects": [
#         { "LogicalObjNum":1,
#           "PhysicalObjNum":1,
#           "FileExtension":"TIF",
#           "FileFmtDesc":"TIFF Images (Black and White)"}
#       ]
#     }
#   },
#   "DocLabels":[ {"label":"ed"}, {"label":"Ann"}]
# }

json_string = "{ \"DocVersions\": { \"1\": { \"version_date\": \"2015-10-06 12:00:00\", \"objects\":[ { \"LogicalObjNum\":1, \"PhysicalObjNum\":1, \"FileExtension\":\"TIF\", \"FileFmtDesc\":\"TIFF Images (Black and White)\"} ] } }, \"DocLabels\":[{\"label\":\"Ed\"},{\"label\": \"Ann\"}]}"

doc_meta = JSON.parse json_string
puts "  Document Labels:"
doc_meta['DocLabels'].each do |l|
  l.each { |lk, lv| puts "    #{lv}" }
end

puts "  Document Versions:"
doc_meta['DocVersions'].each do |k,v|
  puts "    Version #{k} (#{v["version_date"]}):"
  v["objects"].each do |object|
    object.each { |ok, ov| puts "       #{ok} => #{ov}" }
    puts '----------------------------------------------------------'
  end
end