explode_paths.rb

explode_paths.rb

# Inspiration: https://gist.github.com/potatosalad/760726

def explode_paths(input, klass: Hash, key_delimiter: '__', key_transform: ->(key) { key.to_sym })
  recursive_hash = klass.new { |hash, key| hash[key] = klass.new(&hash.default_proc) }

  result = input.to_h.reduce(recursive_hash) do |recursive_acc, (input_key_path, input_value)|
    keys = input_key_path.to_s.split(key_delimiter).map(&key_transform)
    tree = keys.map {|key| [:[], key] }
    tree.push([:[]=, tree.pop[1], input_value])
    tree.reduce(recursive_acc) do |acc, tree_node|
      acc.public_send(tree_node.shift, *tree_node)
    end
    recursive_acc
  end

  result.default = klass.new.default

  result
end

# ===== Usage =====
#
# hash_input = {
#   foo__bar__a: :a,
#   foo__bar__b: :b,
#   foo__baz__c: :c,
#   foo__baz__d: :d
# }
#
# explode_paths(hash_input)
#
# # Outputs:
#
# {
#   foo: {
#     bar: {
#       a: :a,
#       b: :b
#     },
#     baz: {
#       c: :c,
#       d: :d
#     }
#   }
# }
#
# # OR
#
# array_input = [
#   [:foo__bar__a, :a],
#   [:foo__bar__b, :b],
#   [:foo__baz__c, :c],
#   [:foo__baz__d, :d],
# ]
#
# explode_paths(array_input)
#
# # Outputs:
#
# {
#   foo: {
#     bar: {
#       a: :a,
#       b: :b
#     },
#     baz: {
#       c: :c,
#       d: :d
#     }
#   }
# }
#

Thank you!