#33 Making a Plugin

You can sometimes remove a lot of duplication by generating methods dynamic. In this episode I will show you how to create a plugin which does exactly that.

# models/task.rb
stringify_time :due_at

def validate
  errors.add(:due_at, "is invalid") if due_at_invalid?
end

# stringify_time.rb
module StringifyTime
  def stringify_time(*names)
    names.each do |name|
      define_method "#{name}_string" do
        read_attribute(name).to_s(:db) unless read_attribute(name).nil?
      end
      
      define_method "#{name}_string=" do |time_str|
        begin
          write_attribute(name, Time.parse(time_str))
        rescue ArgumentError
          instance_variable_set("@#{name}_invalid", true)
        end
      end
      
      define_method "#{name}_invalid?" do
        instance_variable_get("@#{name}_invalid")
      end
    end
  end
end

# init.rb
class ActiveRecord::Base
  extend StringifyTime
end