Rails：如何使用从初始化程序中调用的 Rake 任务处理图像

Question

I need to get a specific variant of an image when I start the server, which is why I attempt this with a Rake task that I call from within an initializer:

lib/test.rake:

task test: :environment do

  @user = User.find_by_email("thing@domain.com")

  if @user.avatar.attached?
    # FOR DEBUGGING:
    puts "content_type detected is: #{@user.avatar.blob.content_type}"
    puts "ActiveStorage.variable_content_types are: #{ActiveStorage.variable_content_types}"

    # GOAL: This should return the image variant
    puts @user.avatar.variant(:thumbnail).inspect
  end
  
end

When I execute this Rake task from the command line, it works perfectly:

$ rake test

But when it's executed from within the initializer below, it fails with an ActiveStorage::InvariableError :

/home/user/.rbenv/versions/3.0.1/lib/ruby/gems/3.0.0/gems/activestorage-7.0.4/app/models/active_storage/blob/representable.rb:38:in `variant': ActiveStorage::InvariableError (ActiveStorage::InvariableError)
    from /home/user/.rbenv/versions/3.0.1/lib/ruby/gems/3.0.0/gems/activestorage-7.0.4/app/models/active_storage/attachment.rb:66:in `variant'
    from /home/user/.rbenv/versions/3.0.1/lib/ruby/gems/3.0.0/gems/activesupport-7.0.4/lib/active_support/core_ext/module/delegation.rb:304:in `public_send'
    from /home/user/.rbenv/versions/3.0.1/lib/ruby/gems/3.0.0/gems/activesupport-7.0.4/lib/active_support/core_ext/module/delegation.rb:304:in `method_missing'

initializers/my_initializer.rb:

Rails.configuration.after_initialize do

  # Execute only when in DEV, and not when called from within a Rake task
  if Rails.env.development? && !( defined?(Rake) &&
                                  defined?(Rake.application) &&
                                  Rake.application.top_level_tasks.length > 0 )

    # Load the Rake tasks
    Rails.application.load_tasks

    # Test the execution of the Rake task:
    Rake::Task["test"].reenable
    Rake::Task["test"].invoke

  end

end

I have traced the problem back to ActiveStorage.variable_content_types being an empty array, here, instead of the full list of accepted content_types :

["image/png",                                                                                                                                         
 "image/gif",                                                                                                                                         
 "image/jpg",                                                                                                                                         
 "image/jpeg",                                                                                                                                        
 "image/pjpeg",                                                                                                                                       
 "image/tiff",                                                                                                                                        
 "image/bmp",                                                                                                                                         
 "image/vnd.adobe.photoshop",                                                                                       
 "image/vnd.microsoft.icon",                                                                                        
 "image/webp",
 "image/avif",
 "image/heic",
 "image/heif"]

I suppose that somehow ActiveStorage is not quite ready, when the Rake task is called from within the initializer. But I thought that using the .after_initialize hook inside the initializer would solve the issue. Apparently not.

What is the correct way to get ActiveStorage fully ready, in this scenario, so that the image variant can be processed/returned?

Answer 1

Not sure if can help, but I also run a rake task when my app starts. And I have put the code in config/application.rb

module myApp
  class Application < Rails::Application

    ...
    if defined?(Rails::Server)
      config.after_initialize do            
        Rails.application.load_tasks
        Rake::Task["my_task"].invoke            
      end
    end 
  end
end

Though I don't really care at what point it is invoked in the boot sequence. It may not suit your requirements.