HappyMapper::Differ

In the unlikely scenario you use HappyMapper and you need to find differences between two documents, this could be a solution.

Ok, your probably won't use or need this. But since I enjoy writing to myself here is how to use it.

Note: this library is wildly memory inefficient

def left
  %Q{
  <person name="James">
    <item><name>Car</name></item>
    <item><name>Box</name></item>
  </person>
  }
end

def right
  %Q{
  <person name="Carl">
    <item><name>Car</name></item>
    <item><name>Red Box</name></item>
    <item><name>Cup</name></item>
  </person>
  }
end

require 'happymapper_differ'

class Person
  include HappyMapper

  tag 'person'
  attribute :name, String
  has_many :items, "Item"
end

class Item
  include HappyMapper
  has_one :name, String
end

result = HappyMapper::Differ.new(Person.parse(left), Person.parse(right)).diff

result.changed?
#=> true

result.changes
#=> {"name"=>"Carl", "items"=>[#<Item:0x007ffd2d8d5a68 @name="Red Box">, #<Item:0x007ffd2d8d5630 @name="Cup">]}

result.name.changed?
#=> true

result.name.was
#=> "Carl"

result.items[0].changed?
#=> false
result.items[1].changes?
#=> {"name"=>"Red Box"}
result.items[2].changed?
#=> true
result.items[2]
#=> nil
result.items[2].was
#=> #<Item:0x007fde2c045ee0 @name="Cup">

Extended methods

HappyMapper::Differ extends each HappyMapper instance and element with the following methods:

method	purpose
changed?	returns true if this element, or a child has changed
changes	returns a hash with each element or attribute which changed, and changed value
was	returns the prior object from the right. If there is no change this will be the current value.

Contributing

1. Fork it ( https://github.com/pharos-ie/happymapper-differ/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request