I'm just diving into Datamapper (and Sinatra) and have a question about associations. Below are some models I have. This is what I want to implemented. I'm having an issue with Workoutitems and Workout. Workout will be managed separately, but Workoutitems has a single workout associated with each row.

1. Workout - just a list of types of workouts (run, lift, situps, etc)
2. Selected workout - this is the name of a set of workouts, along with notes by the user and trainer. It has a collection of N workoutitems
3. Workoutitems - this takes a workout and a number of repetitions to it that go in the workout set.

class Workout
      include DataMapper::Resource
      property :id,     Serial  #PK id
      property :name,   String, :length=>50,:required=>true  # workout name
      property :description, String, :length=>255  #workout description
end


    class Selectedworkout
      include DataMapper::Resource
      property :id,  Serial
      property :name, String, :length=>50, :required=>true
      property :workout_time, String, :length=>20
      property :user_notes, String, :length=>255
      property :coach_notes, String, :length=>255
      has n, :workoutitems
    end

    class Workoutitem
      include DataMapper::Resource
      property :id, Serial
      property :reps, String, :length=>50, :required=>true
      belongs_to :selectedworkout
    end