Diff tool for deep Ruby hash comparison
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Deep comparison of Ruby Hash objects


Add this line to your application's Gemfile:

gem 'hash_diff'

And then execute:

$ bundle

Or install it yourself as:

$ gem install hash_diff


Easily find the differences between two Ruby hashes.

  left = {
    foo: 'bar',
    bar: 'foo',
    nested: {
      foo: 'bar',
      bar: {
        one: 'foo1'
    num: 1,
    favorite_restaurant: "Shoney's"

  right = {
    foo: 'bar2',
    bar: 'foo2',
    nested: {
      foo: 'bar2',
      bar: {
        two: 'foo2'
    word: 'monkey',
    favorite_restaurant: nil

  hash_diff = HashDiff::Comparison.new( left, right )

Comparison#diff returns the left and right side differences

  hash_diff.diff # => { foo: ["bar", "bar2"], bar: ["foo", "foo2"], nested: { foo: ["bar", "bar2"], bar: { one: ["foo1", HashDiff::NO_VALUE], two: [HashDiff::NO_VALUE, "foo2"] } }, num:  [1, HashDiff::NO_VALUE], word: [HashDiff::NO_VALUE, "monkey"], favorite_restaurant: ["Shoney's", nil] }

Missing keys

When there is a key that exists on one side it will return HashDiff::NO_VALUE to represent a missing key.

Comparison#left_diff returns only the left side differences

  hash_diff.left_diff # => {:foo=>"bar2", :bar=>"foo2", :nested=>{:foo=>"bar2", :bar=>{:one=>HashDiff::NO_VALUE, :two=>"foo2"}}, :num=>HashDiff::NO_VALUE, :favorite_restaurant=>nil, :word=>"monkey"}

Comparison#right_diff returns only the right side differences

  hash_diff.right_diff # => {:foo=>"bar", :bar=>"foo", :nested=>{:foo=>"bar", :bar=>{:one=>"foo1", :two=>HashDiff::NO_VALUE}}, :num=>1, :favorite_restaurant=>"Shoney's", :word=>HashDiff::NO_VALUE}

You can also use these shorthand methods

  HashDiff.diff(left, right)
  HashDiff.left_diff(left, right)
  HashDiff.right_diff(left, right)

Hash#diff is not provided by default, and monkey patching is frowned upon by some, but to provide a one way shorthand call HashDiff.patch!

  # run prior to implementation

  left  = { foo: 'bar', num: 1 }
  right = { foo: 'baz', num: 1 }

  left.diff(right) # => { foo: 'baz' }


Authored by the Engineering Team of Coding ZEAL

Copyright (c) 2017 Zeal, LLC. Licensed under the MIT license.


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