API Code Not Rendering JSON From Controller Properly From Heroku - ruby-on-rails-3

Question

I am trying to write api code that utilizes the JSON rendered from the controller. I was able to successfully get my desired results locally, but when I push to Heroku parts of my JSON is not rendered correctly.
To put in context, I am trying to create a nested JSON with meal information (name, id, etc) and photo urls. Locally the photo urls render correctly in the JSON. However, on Heroku the photo urls show up as null. On Heroku, I have also tested just rendering the url JSON alone and it is getting the urls correctly.
If you know why it is rendering correctly locally and not on Heroku please let me know. Thank you
I create my JSON the following way:
def api
#meals = Meal.all
#urls = Hash.new
#return_val = Array.new
#sorted_meals = Meal.select('meals.name as meal_name, meals.id as meal_id,
COALESCE(sum(meal_ratings.rating), 0) as meal_rating,
restaurants.id as restaurant_id, restaurants.name as restaurant_name').
joins('LEFT JOIN meal_ratings ON meals.id = meal_ratings.meal_id
LEFT JOIN restaurants ON restaurants.id = meals.restaurant_id').
group('meals.name, meals.id, restaurants.id, restaurants.name').
order('meal_rating DESC').all
#meals.each do |meal|
unless meal.meal_photos.empty?
#urls[meal.id] = {"thumb" => meal.meal_photos[0].photo.url(:thumb), "profile" => meal.meal_photos[0].photo.url(:profile)}
end
end
#sorted_meals.each do |meal|
#return_val.push("id" => meal.meal_id, "name" => meal.meal_name,
"rating" => meal.meal_rating, "restaurant" => meal.restaurant_name,
"restaurant_id" => meal.restaurant_id, "urls" => #urls[meal.meal_id])
end
respond_to do |format|
format.html # show.html.erb
format.json { render json: #return_val } # render json: #url render json: #meals
end
end

Answer 1

The problem was due to Postgres. When I query for a meal_id it returned a string and was not working as a hash key, so I was getting nil. After turning the id string into turn an int everything worked fine. Thanks to the help of Sena this has been resolved.