acts_as_votable , undefined method `upvote_by' for nil:NilClass

Question

i am trying to user acts_as_votable gem to make user vote for stars

this is my stars-controller

class StarsController < ApplicationController
    before_filter :authenticate_user!, except: [:index, :show]
    before_action :upvote 
    def index
        @stars = Star.all.order("created_at DESC")
    end

  def upvote 
   # @star = Star.find(params[:id])
   @star.upvote_by current_user
   redirect_to @star
  end

    def show
        @star= Star.find(params[:id])
    end

    def new
    end

    def create
        @star =Star.new(stars_params)
        @star.save

        redirect_to @star
    end




    private 
    def stars_params
        params.require(:star).permit(:name , :description , :image)
    end

end

and this is my star model

 class Star < ActiveRecord::Base


has_many :books

has_attached_file :image, :styles => { :small => "150x150>" }
validates_attachment_presence :image
validates_attachment_size :image, :less_than => 5.megabytes
validates_attachment_content_type :image, :content_type => ['image/jpeg', 'image/png']
acts_as_votable
end

and the routs

Rails.application.routes.draw do
  resources :books

  devise_for :users, path_names: {sign_in: "login", sign_out: "logout"}

  resources :stars do 
    member do 
      put "like" , to: "stars#upvote"

    end
  end


  root 'stars#index'
end

i get this error "undefined method `upvote_by' for nil:NilClass"

thanks

Answer 1

Your problem is not really related to acts_as_votable - your instance variable has not been assigned yet, so practically any method would cause this error. You have to un-comment commented line and change:

before_action :upvote

to

before_action :upvote, except: :index

This logic however seems fishy - why would you like a star to be upvoted when user is editing it? In short: please clarify your requirements.