Rails how to differentiate two columns in controller?

My association are described below:

Konkurrancers belongs to Kategori

Kategori has many Konkurrancers.

In my konkurrancers table i have:

rating_score
ratings
class KategorisController < ApplicationController
  def show
  @kategori = Kategori.where(:cached_slug => params[:id]).first
// Does not work
   @rating = @kate开发者_如何学Pythongori.konkurrancers.rating_score / @kategori.konkurrancers.ratings
  end
end

I get this error in view:

NoMethodError in KategorisController#show

undefined method `rating_score' for #<Class:0x5f3e590>

The column ratings holds the number of ratings and the rating_score holds the rating

And I want to differentiate those two columns as following: rating_score/ratings

How do I create this in my controller?

Since kategori has multiple konkurrancers so konkurrancers is an array. You need to define of which konkurrancers you take the rating_score

You should try:

@kategori.konkurrancers[0].rating_score

Above code will only work if you have at least 1 @kategori.konkurrancers ofcourse

UPDATE

@rating = 0
@kategori.konkurrancers.each do |k|
    @rating += k.rating_score
end

@rating /=  @kategori.konkurrancers.count