Has many through or Has and belongs to many missing ID - ruby-on-rails

Question

Just trying to create a simple workout log here I'm getting this error when I try and create weights
"Workout ID must exist"
Models
class Workout < ApplicationRecord
belongs_to :user
has_many :exercises
has_many :weights, through: :exercises
accepts_nested_attributes_for :exercises, :allow_destroy => true
accepts_nested_attributes_for :weights, :allow_destroy => true
validates :bodypart, presence: true, length: { maximum: 255 }
end
class Weight < ApplicationRecord
belongs_to :exercise
belongs_to :workout
validates :amount, presence: true, length: { maximum: 255 }
validates :reps, presence: true, length: { maximum: 255 }
end
class Exercise < ApplicationRecord
belongs_to :workout
has_many :weights
accepts_nested_attributes_for :weights
validates :name, presence: true
validates_associated :weights
end
After reading a few things I thought that a has many through would be the option for these associations but now I'm not so sure. When I try and create a weight for exercise I get the exercise ID but can't seem to get the workout ID despite a number of attempts. I'm not sure if its simply a controller issue or if Im missing something bigger here.
My Current Weights Controller
class WeightsController < ApplicationController
before_action :authenticate_user!
def new
#weight = Weight.new
end
def create
#exercise = Exercise.find(params[:exercise_id])
#weight = #exercise.weights.build(weight_params)
if #weight.save
flash[:notice] = "Set saved"
redirect_to exercise_path(#exercise)
else
redirect_to exercise_path(#exercise)
flash[:notice] = "#{#weight.errors.full_messages.to_sentence}"
end
end
def edit
end
def update
end
def destroy
weight = Weight.find(params[:id])
#weight.destroy
redirect_to root_path
end
private
def weight_params
params.require(:weight).permit(:amount, :reps)
end
end
Routes.rb
Rails.application.routes.draw do
devise_for :users, controllers: { omniauth_callbacks: "callbacks" }
root 'articles#index'
get '/demo', to: 'static_pages#demo'
get '/about', to: 'static_pages#about'
get '/test', to: 'static_pages#index'
resources :articles
resources :workouts do
resources :exercises
end
resources :exercises do
resources :weights
end
resources :workouts do
member do
put :is_finished
put :unfinish
end
end
resources :exercises do
member do
put :is_finished
put :unfinish
end
end
resources :books, :only => :index
end
Exercises controller
class ExercisesController < ApplicationController
before_action :authenticate_user!
# before_action :set_exercise, except: [:index, :new, :create]
def new
#exercise = Exercise.new
#exercise.weights.new
end
def index
#workout = Workout.find(params[:workout_id])
#exercise = #workout.exercises
end
def create
#workout = Workout.find(params[:workout_id])
#exercise = #workout.exercises.build(exercise_params)
if #exercise.save
redirect_to workout_exercise_path(#workout, #exercise)
flash[:notice] = "Exercise created, enter weight and reps for your first set"
else
redirect_to #workout
flash[:notice] = "#{#exercise.errors.full_messages.to_sentence}"
end
end
def edit
end
def update
#exercise = Exercise.find(params[:id])
if #exercise.update_attributes(exercise_params)
redirect_to exercise_path(#exercise)
else
flash[:notice] = "Something went wrong"
end
end
def show
#exercise = Exercise.find(params[:id])
#weights = #exercise.weights.order('created_at DESC').paginate(page: params[:page], per_page: 5)
end
I do have an ID column for workout_id set on my Weights model but it always populates NULL whenever I can manage to create an exercise. Also, in the rails console I can find a workout and call #workout.weights and it returns the weights associated with the workout just fine. I just can't get the workout ID to populate in Weight model. Wondering if has and belongs to many would be better OR if my has many through is just set up wrong. I did try "inverse_of" without any luck. Any help would be appreciated.

Answer 1

The answer is quite simple. To add reverse functionality, you have to explicitly state it, through the exercise.
in weight.rb remove belongs_to :workout and add the following
def workout
self.exercise.workout
end
Perhaps you will need to add logic to avoid nilClass errors.
Now you do have #weight.workout through #weight.exercise