在后台执行ActionMailer::MailDeliveryJob时调用类时出现以下错误：

[ActiveJob] [ActionMailer::MailDeliveryJob] [f158adfd-e4ac-4b0c-9c9b-5c4076f659d1] Error performing ActionMailer::MailDeliveryJob (Job ID: f158adfd-e4ac-4b0c-9c9b-5c4076f659d1) from Resque(default) in 733.75ms: NameError (uninitialized constant Railgun): 
abc-web | /opt/abc-web/app/models/email_provider.rb:87:in `delivery_method_args'                                                                                                                                                    
abc-web | /opt/abc-web/app/mailers/user_mailer.rb:191:in `set_delivery_settings'

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但它在控制台中加载得很好：

[2] pry(main)> ::Railgun::Mailer
=> Railgun::Mailer

型
如何让MailDeliveryJob查看::Railgun::Mailer类？
ICIM，这行代码片段：

# /opt/abc-web/app/models/email_provider.rb
 82   def delivery_method_args
 83     first_arg = case provider_type&.to_sym
 84                 when :smtp
 85                   :smtp
 86                 when :mailgun
 87                   ::Railgun::Mailer
 88                 else
 89                   raise "Unknown provider type #{provider_type}"
 90                 end
 91     [first_arg, settings]
 92   end

# /opt/abc-web/app/mailers/user_mailer.rb
181   def set_delivery_settings
182     tenant_email_provider = @user.tenant.email_providers.where(enabled: true).take
183 
184     # Fall back to default configuration settings
185     return if tenant_email_provider.nil? || tenant_email_provider.settings.blank?
186 
187     # This validation should probably done in the form
188     raise 'No server address to send to in smtp settings' if tenant_email_provider.server_address_missing?
189     raise 'No api key to send to in mailgun settings' if tenant_email_provider.api_key_missing?
190 
191     delivery_method_args = tenant_email_provider.delivery_method_args
192     mail.delivery_method(*delivery_method_args)
193   end

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