Idle Hacking

Workout 
   has_many :laps

Lap
   has_many :points
   belongs_to :workout

Point
   belongs_to :lap

I'd like to serialize it all. The first approach

render :xml => workout.to_xml(:include => :laps)

Cool, we get workout data with laps, but no points.

Reading through the to_xml implementation it makes sense that you can only get to first level associations. For my purposes, I just wanted to avoid repeating my data model in my rxml files.

Here's what I came up with.

module Builder
  class XmlMarkup
    def add_record!(record,options = {})
      options = {:builder => self,:skip_instruct => true}.merge!(options)
      ActiveRecord::XmlSerializer.new(record, options).serialize
    end

    def add_record_attributes!(record)
      record.attribute_names.each do|name|
        attr = ActiveRecord::XmlSerializer::Attribute.new(name,record)
        tag!( attr.name, attr.value.to_s, attr.decorations )
      end
    end
  end
end

Now, in my rxml view I can write this.

xml.instruct!( :xml, :version=>"1.0", :encoding=>"UTF-8" )
xml.workout do
  xml.add_record_attributes!(@workout)
  xml.laps do
    @workout.laps.each do|lap|
      xml.add_record!(lap, :include => :points)
    end
  end
end