当从 delayed_job 调用时，与 I18n.fallbacks 相关的 Rails ActionView 发生崩溃

Question

我正在尝试从我的 rails 4 应用程序发送一封电子邮件，就像这样（来自控制台的压缩版）：

> ActionMailer::Base.mail(from: 'mail@example.com', to: 'foo@example.com', subject: 'test', body: "Hello, you've got mail!").deliver_later

邮件将由 delayed_lob 发送，在我的本地测试设置中，我是这样触发它的：

> Delayed::Job.last.invoke_job

但是作业崩溃并显示以下消息：

Devise::Mailer#invitation_instructions: processed outbound mail in 56234.1ms
Performed ActionMailer::DeliveryJob from DelayedJob(mailers) in 56880.04ms
TypeError: no implicit conversion of nil into Array
    from /Users/de/.rvm/gems/ruby-2.4.0/gems/actionview-4.2.10/lib/action_view/lookup_context.rb:51:in `concat'
    from /Users/de/.rvm/gems/ruby-2.4.0/gems/actionview-4.2.10/lib/action_view/lookup_context.rb:51:in `block in <class:LookupContext>'
    from /Users/de/.rvm/gems/ruby-2.4.0/gems/actionview-4.2.10/lib/action_view/lookup_context.rb:39:in `initialize_details'
    from /Users/de/.rvm/gems/ruby-2.4.0/gems/actionview-4.2.10/lib/action_view/lookup_context.rb:205:in `initialize'
...

我查看了lookup_context.rb:51GitHub的代码，问题出在这里：

register_detail(:locale) do
      locales = [I18n.locale]
      locales.concat(I18n.fallbacks[I18n.locale]) if I18n.respond_to? :fallbacks  # < crashes here
# from the debugger I got:
# I18n.locale => :de
# I18n.fallbacks => {:en=>[]}

很明显回退不包含我的语言环境 (:de)，这会导致 nil 异常。

显然 I18n.fallbacks 配置不正确。

问题：我该如何解决这个问题？

Answer 1

我在这个博客的帮助下得到了答案post 我发现：https://sjoker.net/2013/12/30/delayed_job-and-localization/
它包含我需要的一半。建议的解决方案如下：

为了传播创建作业时的状态，必须将该状态存储在数据库中的作业对象上，从而将该状态转移到调用作业时。
在博客 post 中，作者仅存储当前语言环境以在邀请时对邮件进行本地化。但是我还需要存储需要一点序列化的 fallbacks。
这是我的解决方案：

# Add a state attributes to delayed_jobs Table
class AddLocaleToDelayedJobs < ActiveRecord::Migration
  def change
    change_table :delayed_jobs do |t|
      t.string :locale    # will hold the current locale when the job is invoked
      t.string :fallbacks # ...
    end
  end
end

# store the state when creating the job
Delayed::Worker.lifecycle.before(:enqueue) do |job|
  # If Locale is not set
  if(job.locale.nil? || job.locale.empty? && I18n.locale.to_s != I18n.default_locale.to_s)
    job.locale    = I18n.locale
    job.fallbacks = I18n.fallbacks.to_json
  end
end

# retrieve the state when invoking the job
Delayed::Worker.lifecycle.around(:invoke_job) do |job, &block|
  # Store locale of worker
  savedLocale        = I18n.locale
  savedFallbacks     = I18n.fallbacks

  begin
    # Set locale from job or if not set use the default
    if(job.locale.nil?)
      I18n.locale    = I18n.default_locale
    else
      h              = JSON.parse(job.fallbacks, {:symbolize_names => true})
      I18n.fallbacks = h.each { |k, v| h[k] = v.map(&:to_sym) } # any idea how parse this more elegantly?
      I18n.locale    = job.locale
    end

    # now really perform the job
    block.call(job)

  ensure
    # Clean state from before setting locale
    I18n.locale      = savedLocale
    I18n.fallbacks   = savedFallbacks
  end
end

Answer 2

您需要像下面这样配置您的默认和后备语言环境

config.i18n.default_locale = :de
config.i18n.fallbacks = { de: :en }

请试试这个。如果找不到 :de

，它将回退到 :en

当从 delayed_job 调用时，与 I18n.fallbacks 相关的 Rails ActionView 发生崩溃

Crash in Rails ActionView related to I18n.fallbacks when invoked from delayed_job

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