Undefined method `image' for #<ActiveStorage::Attachment: - ruby-on-rails

Question

I'm trying to implement photo upload using DropzoneJS and Active Storage but at this point, my app throws undefined method 'image' for #<ActiveStorage::Attachment:0x00007fa51201dd80> error.
models/car.rb
index.html.erb
My Gemfile. Do i need to uncomment image-processing gem to enable and use?
source 'https://rubygems.org'
git_source(:github) { |repo| "https://github.com/#{repo}.git" }
ruby '2.6.5'
# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
gem 'rails', '~> 6.0.0'
# Use sqlite3 as the database for Active Record
gem 'sqlite3', '~> 1.4'
#gem 'pg'
# Use Puma as the app server
gem 'puma', '~> 3.11'
# Use SCSS for stylesheets
gem 'sass-rails', '~> 5'
# Transpile app-like JavaScript. Read more: https://github.com/rails/webpacker
gem 'webpacker', '~> 4.0'
# Turbolinks makes navigating your web application faster. Read more: https://github.com/turbolinks/turbolinks
gem 'turbolinks', '~> 5'
# Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder
gem 'jbuilder', '~> 2.7'
# Use Redis adapter to run Action Cable in production
# gem 'redis', '~> 4.0'
# Use Active Model has_secure_password
# gem 'bcrypt', '~> 3.1.7'
# Use Active Storage variant
# gem 'image_processing', '~> 1.2'
# Reduces boot times through caching; required in config/boot.rb
gem 'bootsnap', '>= 1.4.2', require: false
group :development, :test do
# Call 'byebug' anywhere in the code to stop execution and get a debugger console
gem 'byebug', platforms: [:mri, :mingw, :x64_mingw]
end
group :development do
# Access an interactive console on exception pages or by calling 'console' anywhere in the code.
gem 'web-console', '>= 3.3.0'
gem 'listen', '>= 3.0.5', '< 3.2'
# Spring speeds up development by keeping your application running in the background. Read more: https://github.com/rails/spring
gem 'spring'
gem 'spring-watcher-listen', '~> 2.0.0'
#Provides better error page for Rails and other Rack apss.
gem 'better_errors', '~> 2.5', '>= 2.5.1'
end
group :test do
# Adds support for Capybara system testing and selenium driver
gem 'capybara', '>= 2.15'
gem 'selenium-webdriver'
# Easy installation and use of web drivers to run system tests with browsers
gem 'webdrivers'
end
# Windows does not include zoneinfo files, so bundle the tzinfo-data gem
gem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw, :jruby]
gem 'bootstrap', '~> 4.4.1'
gem 'devise', '~> 4.7', '>= 4.7.1'
gem 'jquery-rails'
gem 'omniauth', '~> 1.9'
gem 'omniauth-facebook', '~> 5.0'
#new gems
group :development, :production do
gem 'capistrano', '~> 3.11', require: false
gem 'capistrano-bundler', require: false
gem 'capistrano-rails', '~> 1.4', require: false
gem 'capistrano-passenger', '~> 0.2.0'
gem 'capistrano-rbenv', '~> 2.1', '>= 2.1.4', github: 'capistrano/rbenv', require: false
end
#gem 'capistrano', '~> 3.11'
#gem 'capistrano-rails', '~> 1.4'
#gem 'capistrano-passenger', '~> 0.2.0'
#gem 'capistrano-rbenv', '~> 2.1', '>= 2.1.4'
gem 'jquery-ui-rails', '~> 5.0'
This is a bit confusing as i'm new to this.
Am i suppose to create a Controller for Photos?
Do i need to add a certain gem too?
How do i fix this?

Answer 1

You don't need to create another model. All you need to make sure you add has_many_attached :photos to your model file and using url_for(self.photos[0]) for getting url. You can also go with self.photos[0].service_url
Edit after comments:
You are getting same NoMethodError because there is no image method defined on cover_photo. One way of correcting your can be like this
def cover_photo(size_x, size_y)
if self.photos.length > 0
self.photos[0].variant(resize_to_limit: [size_x, size_y]).processed.service_url
else
"blank.jpg"
end
end