validates_timeliness/lib/validates_timeliness/attribute_methods.rb

# For Rails 2.0.x:
#   This module adds method to create reader method for Time attributes
#   to allow for invalid date checking. If date is invalid then returns nil for
#   time value.
#
# For Rails >= 2.1  
#   This module overrides these AR methods to allow a time value passed to a column 
#   write method to be stored as is and converts it to a time and caches on read.
#   This differs from the normal AR behvaviour where the value is converted and
#   cached on write.
#
#   This allows the before_type_cast method for the column to return the actual 
#   value passed to it, treating time columns like all other column types.
module ValidatesTimeliness
  module AttributeMethods
    
    def self.included(base)
      if ActiveRecord::VERSION::STRING < '2.1'
        base.extend ClassMethods::Old
      else
        base.extend ClassMethods::New
      end
    end
    
    module ClassMethods
      # ActiveRecord >= 2.1
      module New
        def define_read_method_for_time_zone_conversion(attr_name)
          method_body = <<-EOV          
            def #{attr_name}(reload = false)
              cached = @attributes_cache['#{attr_name}']
              return cached if cached && !reload
              time = read_attribute_before_type_cast('#{attr_name}')
              if time.acts_like?(:time)
                time = time.in_time_zone
              elsif time
                # check invalid date
                time.to_date rescue time = nil
                time = time.in_time_zone if time
              end
              @attributes_cache['#{attr_name}'] = time
            end
          EOV
          evaluate_attribute_method attr_name, method_body
        end
        
        def define_write_method_for_time_zone_conversion(attr_name)
          method_body = <<-EOV
            def #{attr_name}=(time)
              if time.acts_like?(:time)
                time = time.in_time_zone rescue time            
              end
              write_attribute(:#{attr_name}, time)
            end
          EOV
          evaluate_attribute_method attr_name, method_body, "#{attr_name}="
        end
      end # New
    
      # ActiveRecord < 2.1
      module Old
        def define_attribute_methods
          return if generated_methods?
          columns_hash.each do |name, column|
            unless instance_method_already_implemented?(name)
              if self.serialized_attributes[name]
                define_read_method_for_serialized_attribute(name)
              else
                if column.klass == Time                  
                  define_read_method_for_time_attribute(name.to_sym)
                else 
                  define_read_method(name.to_sym, name, column)
                end
              end
            end

            unless instance_method_already_implemented?("#{name}=")
              define_write_method(name.to_sym)
            end

            unless instance_method_already_implemented?("#{name}?")
              define_question_method(name)
            end
          end
        end

        def define_read_method_for_time_attribute(attr_name)
          method_body = <<-EOV          
          def #{attr_name}(reload = false)
            cached = @attributes_cache['#{attr_name}']
            return cached if cached && !reload
            time = read_attribute_before_type_cast('#{attr_name}')
            unless time.acts_like?(:time)
              # check invalid date
              time.to_date rescue time = nil
              time = time.to_time if time
            end
            @attributes_cache['#{attr_name}'] = time
          end
          EOV
          evaluate_attribute_method attr_name, method_body
        end
      end # Old

    end # ClassMethods    
  end
end