Ruby- How to add comments list to user's dashboard? - ruby-on-rails

Question

I have three tables: books, comments and users. Tables are related. Users can login and then comment on books. Users have a dashboard. How can I make users see the comments that have been made to their books on their dashboard?
Here are the models,
book.rb:
class Book < ApplicationRecord
validates :title, presence: true
validates :author, presence: true
belongs_to :user
has_many :comments
end
comment.rb:
class Comment < ApplicationRecord
belongs_to :book
belongs_to :user
scope :approved, -> {where(status: true)}
end
user.rb:
class User < ApplicationRecord
before_create :set_username
has_many :books
has_many :comments
devise :database_authenticatable, :registerable,
:recoverable, :rememberable, :validatable
attr_writer :login
def login
#login || self.username || self.email
end
# validates_length_of :username,
# :within => 5..50,
# :too_short => " is too short, must be at least 5 characters.",
# :presence => true
private
def set_username
self.username = self.email.split("#").first
end
def self.find_first_by_auth_conditions(warden_conditions)
conditions = warden_conditions.dup
if login = conditions.delete(:login)
where(conditions).where(["lower(username) = :value OR lower(email) = :value", { :value => login.downcase }]).first
else
if conditions[:username].nil?
where(conditions).first
else
where(username: conditions[:username]).first
end
end
end
end
dashboard controller:
class DashboardController < ApplicationController
def index
#books = current_user.books
end
end

Answer 1

Since you already have the book, you can also include the comments to reduce n+1. So in your DashboardController you can modify the statement you have with #books = current_user.books.includes(:comments). This will collect all of the comments for that user's books. Then in the view you can iterate through them like this. Where you can display them however you want, ie, ol/ul with children li for teh comments
<% #books.each do |book| %>
<%= book.title %>
<%= book.author %>
<p>Comments:</p>
<% book.comments.each do |comment| %>
<%= comment.text %>
<% end %>
<% end %>

Answer 2

I have some suggestion for you.
You can write like this
class DashboardController < ApplicationController
def index
#books = current_user.books.includes(:comments)
end
end
It will get all of the comments you need, especially you also avoid n+1 query.
Or you can also write
class DashboardController < ApplicationController
def index
#books = current_user.books
#comments = current_user.comments.where('id = ?', #books.pluck(:id))
end
end