JSON Patching and Diffing..

json_diff_and_patch.rb

require 'jsondiff' # https://github.com/francois2metz/jsondiff
require 'json/patch' # https://github.com/guillec/json-patch

def test_1
  hash_1 = {a: {b:"sexy key"}, c: [1,2,3], x: "gonna remove this one"}
  json_1 = JSON.generate(hash_1)

  hash_2 = {a: {b:"new key", b2: "sexier key"}, c: [2,3,4], d: "a new key entirely"}
  json_2 = JSON.generate(hash_2)

  patch = JsonDiff.generate(hash_1, hash_2)
  # => [
  #   {:op=>:replace, :path=>"/a/b", :value=>"new key"},
  #   {:op=>:add, :path=>"/a/b2", :value=>"sexier key"},
  #   {:op=>:replace, :path=>"/c/0", :value=>2},
  #   {:op=>:replace, :path=>"/c/1", :value=>3},
  #   {:op=>:replace, :path=>"/c/2", :value=>4},
  #   {:op=>:add, :path=>"/d", :value=>"a new key entirely"},
  #   {:op=>:remove, :path=>"/x"}
  # ]
  json_patch = JSON.generate(patch)

  JSON.patch(json_1,json_patch) == json_2
  # => true
end

puts "TEST 1 Passed: #{test_1}"

def test_2
  docs = [
    { },
    { key1: "value1" },
    { key1: "value1", key2: [1,2,3] },
    { key1: "value1", key2: [1,3], key3: "value3" },
    { key2: [1,2,3], key3: "value3" },
    { key2: [1,2,3], key3: "value3", key4: "value4" }
  ]

  patches = [
    (JsonDiff.generate(docs[-1],docs[-2])),
    (JsonDiff.generate(docs[-2],docs[-3])),
    (JsonDiff.generate(docs[-3],docs[-4])),
    (JsonDiff.generate(docs[-4],docs[-5])),
    (JsonDiff.generate(docs[-5],docs[-6]))
  ]

  start_doc = docs.last
  end_doc = docs.first

  patched_doc = patches.inject(start_doc) do |doc, patch|
    json_doc = JSON.generate doc
    json_patch = JSON.generate patch

    puts
    puts "Applying patch to JSON:"
    puts "Doc:\t#{json_doc}"
    puts "Patch:\t#{json_patch}"

    new_doc = JSON.patch(json_doc, json_patch)

    puts "Result:\t#{new_doc}"
    puts

    JSON.parse(new_doc)
  end

  end_doc == patched_doc
end

puts "TEST 2 Passed: #{test_2}"