Module: Philiprehberger::JsonMerge::MergePatch

Defined in:
lib/philiprehberger/json_merge/merge_patch.rb

Overview

RFC 7396 JSON Merge Patch implementation

Recursively merges a patch into a target document. Hash values are deep merged, nil values remove keys.

Class Method Summary collapse

Class Method Details

.call(target, patch) ⇒ Hash, Object

Apply a merge patch to a target document

Parameters:

  • target (Hash, Object) —

    the target document

  • patch (Hash, Object) —

    the merge patch to apply

Returns:

  • (Hash, Object) —

    the patched document



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# File 'lib/philiprehberger/json_merge/merge_patch.rb', line 15

def self.call(target, patch)
  return patch unless patch.is_a?(Hash)

  result = target.is_a?(Hash) ? target.dup : {}

  patch.each do |key, value|
    if value.nil?
      result.delete(key)
    elsif value.is_a?(Hash)
      existing = result[key]
      result[key] = call(existing.is_a?(Hash) ? existing : {}, value)
    else
      result[key] = value
    end
  end

  result
end

.generate(source, target) ⇒ Hash?

Generate a merge patch that transforms source into target

Parameters:

  • source (Hash, Object) —

    the source document

  • target (Hash, Object) —

    the target document

Returns:

  • (Hash, nil) —

    the merge patch, or nil if documents are equal



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# File 'lib/philiprehberger/json_merge/merge_patch.rb', line 39

def self.generate(source, target)
  return target unless source.is_a?(Hash) && target.is_a?(Hash)

  patch = {}

  # Keys removed or changed in target
  source.each do |key, value|
    if target.key?(key)
      if value.is_a?(Hash) && target[key].is_a?(Hash)
        sub_patch = generate(value, target[key])
        patch[key] = sub_patch unless sub_patch.nil? || (sub_patch.is_a?(Hash) && sub_patch.empty?)
      elsif value != target[key]
        patch[key] = target[key]
      end
    else
      patch[key] = nil
    end
  end

  # Keys added in target
  target.each do |key, value|
    patch[key] = value unless source.key?(key)
  end

  patch.empty? ? {} : patch
end