Rails is rendering views very slowly - ruby-on-rails

Question

I'm still really new to Rails and working on a practice project lab and I ran into an issue where the view was rendering really slow.
Any and all help would be appreciated!
I also received this error:
SystemStackError (stack level too deep):
app/models/blogger.rb:23:in `popular_post'
app/views/bloggers/show.html.erb:13:in `_app_views_bloggers_show_html_erb__247812415140953454_70240453389320'
Gemfile
gem 'rails', '~> 5.1.6'
gem 'sqlite3'
gem 'puma', '~> 3.7'
gem 'sass-rails', '~> 5.0'
gem 'uglifier', '>= 1.3.0'
gem 'faker'
gem 'coffee-rails', '~> 4.2'
gem 'turbolinks', '~> 5'
gem 'jbuilder', '~> 2.5'
group :development, :test do
gem 'byebug', platforms: [:mri, :mingw, :x64_mingw]
gem 'capybara', '~> 2.13'
gem 'selenium-webdriver'
end
group :development do
gem 'web-console', '>= 3.3.0'
gem 'listen', '>= 3.0.5', '< 3.2'
gem 'spring'
gem 'spring-watcher-listen', '~> 2.0.0'
end
gem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw, :jruby]
My classes are Blogger, Destination, and Post (Blogger -< Post >- Destination). Below is the code for the Blogger model, show page, and controller (I didn't work on code for anything else yet, except the Blogger index but works and is just a list)
blogger.rb
class Blogger < ApplicationRecord
has_many :destinations
has_many :posts, through: :destinations
validates :name, uniqueness: true
validates :age, numericality: { greater_than: 0, message: ": You're Too Young" }
validates :bio, length: { :minimum => 30 }
def self.average_age
ages = self.all.sum do |blogger|
blogger.age
end
(ages / self.all.count)
end
def total_likes
self.posts.sum do |post|
post.likes
end
end
def popular_post
self.posts.max_by do |a|
a.likes
end
end
def top_five
self.destinations.sort_by do |destination|
destination.post_count
end.take(5)
end
end
blogger show page
<h1> <%= #blogger.name %> </h1>
<br />
<p> Age: <%= #blogger.age %> </p>
<br />
<br />
<p> Bio: <%= #blogger.bio %> </p>
<br />
<br />
<%= link_to #blogger.popular_post.title, post_path(#blogger.popular_post) %>
<br />
<%= #blogger.top_five %>
blogger controller
class BloggersController < ApplicationController
def index
#bloggers = Blogger.all
end
def show
#blogger = Blogger.find(params[:id])
end
def new
#blogger = Blogger.new
end
def create
#blogger = Blogger.create(blogger_params)
if #blogger.valid?
#blogger.save
redirect_to blogger_path(#blogger)
else
flash[:my_errors] = #blogger.errors.full_messages
redirect_to new_blogger_path
# render :new
end
end
private
def blogger_params
params.require(:blogger).permit(:name, :bio, :age)
end
end

Answer 1

I think that you need to modify this method
def popular_post
self.posts.max_by do |a|
a.likes
end
end
max_by is a method for an Enumerable class and you call it on a Post class, so this will not work properly. I would suggest that you use something like posts.order('likes DESC').first if likes is an Integer.
Also tiny hint you don't need to use all this self in an object and in class methods. Rails would assume that you call it on an object if this is an object method or you call it on a relation if this is a class method.

Answer 2

The methods total_likes, popular_post and top_five all work by assuming your associations are "arrays" (enumerations). While this works, definitally for smaller examples, it is less optimal. Because working on an array also requires the complete array to be loaded from the database first, and then do your calculations locally on a complete set (in memory). A database is optimally suited to perform such tasks (querying).
For instance, top_five can better be written to sort on the database and then only fetch the 5 first (most popular).
def top_five
destinations.order(post_count: :desc).limit(5)
end
(this is assuming that :post_count is an actual field in the database.
Similarly we can improve the other methods:
def total_likes
posts.sum(:likes)
end
just use the database: this will start a single query to return the sum of likes for all the posts of the blogger.
def popular_post
posts.order(likes: :desc).limit(1).first
end
We sort on descending likes and the select the first one. The limit 1 tells we only want to retrieve one item, but this still returns an array, so we want the first returned item.
This should improve your performance.