Model associations callbacks

Question

I would like to add a review section to my app. To be more specific, a user can leave a review for a shop and the shop can then reply to that review. But I'm not sure if the model associations and review table migrations I have are correct.

class User < ActiveRecord::Base
  has_many :reviews
end

class Review < ActiveRecord::Base
  belongs_to :user
end

class ReviewReply < ApplicationRecord
  belongs_to :user, optional: true
  belongs_to :review, optional: true
end


class Shop < ActiveRecord::Base
  has_many :reviews
end

class CreateReviews < ActiveRecord::Migration[6.0]
  def change
    create_table :reviews do |t|
      t.text :body
      t.integer :rating
      t.references :shop, null: false, foreign_key: true
      t.references :user, null: false, foreign_key: true

      t.timestamps
    end
  end
end

Answer 1

Architecture:

1. CALCULATING RATING

console:

rails g migration add_rating

migration:

  def change
    add_column :shops, :average_rating, :integer, default: 0, null: false
    add_column :reviews, :rating, :integer, default: 0, null: false
  end

user.rb

has_many :reviews

shop.rb

  has_many :reviews

  def update_rating
    if reviews.any? && reviews.where.not(rating: nil).any?
      update_column :average_rating, reviews.average(:rating).round(2).to_f
    else
      update_column :average_rating, 0
    end
  end

review.rb

  belongs_to :user
  belongs_to :shop
  has_one :review_reply

  after_save do
    unless rating.nil? || rating.zero?
      shop.update_rating
    end
  end

  after_destroy do
    shop.update_rating
  end

review_reply.rb

  belongs_to :review

2. REPLY TO A REVIEW

views/reviews/show.html.erb:

<% unless @review.review_reply.present? %>
  <%= link_to "Write a Reply", new_review_reply_path(review_id: @review.id) %>
<% end %>

views/review_replies/form.html.erb

= f.input :review_id, input_html: {value: params[:review_id]}, as: :hidden