Can't Display a value from my rails model - ruby-on-rails

Question

I'm new to Ruby on Rails and I started with a scaffold and added another model manually. I can't seem to get the values from the model I manually generated to display in my index view.
My first model is for Golf Courses names, city, par, and hole_id. The second model is the amount of holes for each course. For some reason I can't get the hole amount to display Below is my code.
Models
class Course < ActiveRecord::Base
has_many :holes
end
class Hole < ActiveRecord::Base
belongs_to :course
end
Controller
class CoursesController < ApplicationController
before_action :set_course, only: [:show, :edit, :update, :destroy]
# GET /courses
# GET /courses.json
def index
#courses = Course.all
#holes = Hole.all
end
# GET /courses/1
# GET /courses/1.json
def show
end
# GET /courses/new
def new
#course = Course.new
end
# GET /courses/1/edit
def edit
end
# POST /courses
# POST /courses.json
def create
#course = Course.new(course_params)
respond_to do |format|
if #course.save
format.html { redirect_to #course, notice: 'Course was successfully created.' }
format.json { render :show, status: :created, location: #course }
else
format.html { render :new }
format.json { render json: #course.errors, status: :unprocessable_entity }
end
end
end
# PATCH/PUT /courses/1
# PATCH/PUT /courses/1.json
def update
respond_to do |format|
if #course.update(course_params)
format.html { redirect_to #course, notice: 'Course was successfully updated.' }
format.json { render :show, status: :ok, location: #course }
else
format.html { render :edit }
format.json { render json: #course.errors, status: :unprocessable_entity }
end
end
end
# DELETE /courses/1
# DELETE /courses/1.json
def destroy
#course.destroy
respond_to do |format|
format.html { redirect_to courses_url, notice: 'Course was successfully destroyed.' }
format.json { head :no_content }
end
end
private
# Use callbacks to share common setup or constraints between actions.
def set_course
#course = Course.find(params[:id])
end
# Never trust parameters from the scary internet, only allow the white list through.
def course_params
params.require(:course).permit(:name, :city, :hole_id)
end
end
View
<p id="notice"><%= notice %></p>
<p>
<strong>Name:</strong>
<%= #course.name %>
</p>
<p>
<strong>City:</strong>
<%= #course.city %>
</p>
<p>
<strong>Hole:</strong>
<%= #course.holes %>
</p>
<%= link_to 'Edit', edit_course_path(#course) %> |
<%= link_to 'Back', courses_path %>

Answer 1

<%= #course.holes %> gives you an ActiveRecord_Associations_CollectionProxy
You need to ask for its size, length or its count to get the total amount of holes that belong to #course which means you have to say #course.holes.size, #course.holes.length or #course.holes.count. Check the documentation for the differences between these three.