Wrap JSON data with type-safe methods

base.rb

module JsonWrapper
  class Base
    MAPPING_TYPES = {
      array: :to_a,
      boolean: :to_bool,
      date: :to_date,
      datetime: :to_datetime,
      float: :to_f,
      hash: :to_h,
      integer: :to_i,
      string: :to_s
    }.freeze

    attr_reader :json_data

    def initialize json_hash = {}
      @json_data = json_hash
    end

    #
    def self.map_json keypath, method_name, type = :string
      define_method method_name do
        value = instance_variable_get("@#{method_name.to_s}")

        unless value.nil?
          return value
        else
          begin
            keys = keypath.split('.')
            transformer = MAPPING_TYPES[type]

            # grab the last part of the keypath
            key = keys.pop

            # Walk the first part of the keypath
            data = @json_data
            while keys.length > 0 do
              data = data[(keys.shift).to_s].try(:to_h)
            end

            value = data[key.to_s].try(transformer)

            if block_given?
              value = yield(value)
            end

            instance_variable_set("@#{method_name.to_s}", value)
          rescue StandardError => e
            Rails.logger.error "[RevelApi::Base] #{e}"
            return nil
          end
        end
      end
    end

  end
end

example.json

{
  "id": 10019348,
  "name": {
    "first": "Jesse",
    "last": "Curry"
  }
}

example.rb

class Person < JsonWrapper::Base
  map_json 'id', :id, :integer
  map_json 'name.first', :first_name, :string
  map_json 'name.last', :last_name, :string do |l|
    l.try(:upcase)
  end
end

to_bool.rb

# From: http://drawingablank.me/blog/ruby-boolean-typecasting.html

class String
  def to_bool
    return true if self == true || self =~ (/^(true|t|yes|y|1)$/i)
    return false if self == false || self.blank? || self =~ (/^(false|f|no|n|0)$/i)
    raise ArgumentError.new("invalid value for Boolean: \"#{self}\"")
  end
end

class Fixnum
  def to_bool
    return true if self == 1
    return false if self == 0
    raise ArgumentError.new("invalid value for Boolean: \"#{self}\"")
  end
end

class TrueClass
  def to_i; 1; end
  def to_bool; self; end
end

class FalseClass
  def to_i; 0; end
  def to_bool; self; end
end

class NilClass
  def to_bool; false; end
end