rails model has_many :through associations

Question

I am trying to get my relationships worked out but I am having trouble using the associations.

So I have three models Workout, Exercise and

Answer 1

Your code looks OK. Bug maybe has_and_belongs_to_many is a better choice. See Choosing Between has_many :through and has_and_belongs_to_many

Answer 2

Ok, so your WorkoutExercises table can't be empty. This is how it should look:

class CreateWorkoutExercises < ActiveRecord::Migration
  def change
    create_table :WorkoutExercises do |t|
      t.integer :exercise_id, :null => false
      t.integer :workout_id, :null => false

      t.timestamps
    end

    # I only added theses indexes so theoretically your database queries are faster.
    # If you don't plan on having many records, you can leave these 2 lines out.
    add_index :WorkoutExercises, :exercise_id
    add_index :WorkoutExercises, :workout_id
  end
end

Also, you can name this table whatever you'd like, it doesn't have to be WorkoutExercises. However, if you were using a has_and_belongs_to_many relationship, your table would have to mandatorily be named ExercisesWorkout. Notice how Exercises comes before Workout. The names have to be alphabetically ordered. Don't ask me why, it's just a Rails convention.

So, in this case, you'll do fine with your table being named WorkoutExercises. But if I were you, I'd change it to ExercisesWorkout, just in case, so that you never get it wrong.