rails instance methods not working on relation

Question

I feel like I am making a syntax error.

I am trying to define an instance method in the model, that then gets called with an instance receiver. but the output is nilClass.

What am I doing wrong?

model

class Park < ActiveRecord::Base

  has_many :reviews

  def percentages
    @percentages = Array.new(5, 0)
    if reviews.any?
      5.downto(1).each_with_index do |val, index|
        @percentages[index] = (reviews.with_stars(val).size) * 100 / (reviews_count)
      end
      @percentages
    end
  end

end

controller

class ParksController < ApplicationController

  def show
     @park = Park.find(params[:id])
     @percentages = @park.percentages
  end

end

view

= @percentages[0]

output

undefined method `[]' for nil:NilClass

Answer 1

You should explicitly return the @percentages after the if.

def percentages
  @percentages = Array.new(5, 0)
  if reviews.any?
    5.downto(1).each_with_index do |val, index|
      @percentages[index] = (reviews.with_stars(val).size) * 100 / (reviews_count)
    end
  end
  @percentages
end

Moreover, you don't need an instance variable in the method. A simple variable would be enough.

def percentages
  percentages = Array.new(5, 0)
  if reviews.any?
    5.downto(1).each_with_index do |val, index|
      percentages[index] = (reviews.with_stars(val).size) * 100 / (reviews_count)
    end
  end
  percentages
end