Module: ActiveRecord::AttributesWithDefaults::ClassMethods

Defined in:
lib/attribute_defaults.rb

Instance Method Summary collapse

Instance Method Details

#attr_default(sym, *args, &block) ⇒ Object

Set defaults. Examples:

attr_default    :age, 12
attr_default    :description, '(none)'
attr_default    :age do |record|
  Time.zone.year - record.dob.year
end
attr_default    :description, '(none)', :if => :blank
attr_default    :description, '(none)', :persisted => false
attr_default    :description, :default => '(none)', :persisted => false



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# File 'lib/attribute_defaults.rb', line 19

def attr_default(sym, *args, &block)
  options = args.extract_options!
  default = options.delete(:default) || args.shift
  raise 'Default value or block required' unless !default.nil? || block

  evaluator = "__eval_attr_default_for_#{sym}".to_sym
  setter    = "__set_attr_default_for_#{sym}".to_sym
  block   ||= default.is_a?(Proc) ? default : proc { default }

  after_initialize setter.to_sym
  define_method(evaluator, &block)

  module_eval(<<-EVAL, __FILE__, __LINE__ + 1)
    def #{setter}
      #{'return if persisted?' if options[:persisted] == false}
      return unless self.#{sym}.send(:#{options[:if] || 'nil?'})
      value = #{evaluator}#{'(self)' unless block.arity.zero?}
      self.#{sym} = value.duplicable? ? value.dup : value
    rescue ActiveModel::MissingAttributeError
    end
  EVAL
  private evaluator, setter
end

#attr_defaults(pairs) ⇒ Object

Default mass-assignment. Examples:

attr_defaults   :description => '(none)', :age => 12
attr_defaults   :description => '(none)', :age => lambda {|r| Time.zone.year - r.dob.year }
attr_defaults   :description => '(none)', :age => { :default => 12, :persisted => false }



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# File 'lib/attribute_defaults.rb', line 47

def attr_defaults(pairs)
  pairs.each do |pair|
    attr_default *pair
  end
end