#<ActiveStorage::Attachment: 的未定义方法“图像”：

Question

我正在尝试使用 DropzoneJS 和 Active Storage 实现照片上传，但此时，我的应用会抛出 undefined method 'image' for #<ActiveStorage::Attachment:0x00007fa51201dd80> 错误。

models/car.rb

index.html.erb

我的宝石文件。我是否需要取消注释图像处理 gem 才能启用和使用？

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'

这有点令人困惑，因为我是新手。

我想为Photos 创建一个控制器吗？

我也需要添加某个宝石吗？

我该如何解决这个问题？

Answer 1

您不需要创建另一个模型。您只需确保将has_many_attached :photos 添加到模型文件并使用url_for(self.photos[0]) 获取url。你也可以选择self.photos[0].service_url

在 cmets 之后编辑：

您会得到相同的 NoMethodError，因为在 cover_photo 上没有定义图像方法。一种纠正方法是这样的

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