Question

给定一个调用回调throw(:abort)的模型，如何在不修改回调的情况下确定哪个回调？

例如，以下型号......

class OddDuck < ApplicationRecord
  before_save :random_abort_1
  before_save :random_abort_2

  private

  def random_abort_1
    if Random.rand(2) == 1
      throw(:abort)
    end
  end

  def random_abort_2
    if Random.rand(2) == 1
      throw(:abort)
    end
  end
end

......有时会无法保存...

$ rails c
Running via Spring preloader in process 81303
Loading development environment (Rails 5.0.0.1)
irb(main):001:0> OddDuck.create!
   (0.1ms)  begin transaction
   (0.1ms)  rollback transaction
ActiveRecord::RecordNotSaved: Failed to save the record
    from /Users/alice/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activerecord-5.0.0.1/lib/active_record/persistence.rb:152:in `save!'
    from /Users/alice/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activerecord-5.0.0.1/lib/active_record/validations.rb:50:in `save!'
    from /Users/alice/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activerecord-5.0.0.1/lib/active_record/attribute_methods/dirty.rb:30:in `save!'
    from /Users/alice/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activerecord-5.0.0.1/lib/active_record/transactions.rb:324:in `block in save!'
    from /Users/alice/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activerecord-5.0.0.1/lib/active_record/transactions.rb:395:in `block in with_transaction_returning_status'
    from /Users/alice/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activerecord-5.0.0.1/lib/active_record/connection_adapters/abstract/database_statements.rb:232:in `block in transaction'
    from /Users/alice/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activerecord-5.0.0.1/lib/active_record/connection_adapters/abstract/transaction.rb:189:in `within_new_transaction'
    from /Users/alice/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activerecord-5.0.0.1/lib/active_record/connection_adapters/abstract/database_statements.rb:232:in `transaction'
    from /Users/alice/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activerecord-5.0.0.1/lib/active_record/transactions.rb:211:in `transaction'
    from /Users/alice/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activerecord-5.0.0.1/lib/active_record/transactions.rb:392:in `with_transaction_returning_status'
    from /Users/alice/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activerecord-5.0.0.1/lib/active_record/transactions.rb:324:in `save!'
    from /Users/alice/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activerecord-5.0.0.1/lib/active_record/suppressor.rb:45:in `save!'
    from /Users/alice/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activerecord-5.0.0.1/lib/active_record/persistence.rb:51:in `create!'
    from (irb):1
    from /Users/alice/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/railties-5.0.0.1/lib/rails/commands/console.rb:65:in `start'
    from /Users/alice/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/railties-5.0.0.1/lib/rails/commands/console_helper.rb:9:in `start'
    from /Users/alice/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/railties-5.0.0.1/lib/rails/commands/commands_tasks.rb:78:in `console'
    from /Users/alice/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/railties-5.0.0.1/lib/rails/commands/commands_tasks.rb:49:in `run_command!'
    from /Users/alice/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/railties-5.0.0.1/lib/rails/commands.rb:18:in `<top (required)>'
    from /Users/alice/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activesupport-5.0.0.1/lib/active_support/dependencies.rb:293:in `require'
    from /Users/alice/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activesupport-5.0.0.1/lib/active_support/dependencies.rb:293:in `block in require'
    from /Users/alice/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activesupport-5.0.0.1/lib/active_support/dependencies.rb:259:in `load_dependency'
    from /Users/alice/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activesupport-5.0.0.1/lib/active_support/dependencies.rb:293:in `require'
    from /Users/alice/Desktop/site/bin/rails:9:in `<top (required)>'
    from /Users/alice/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activesupport-5.0.0.1/lib/active_support/dependencies.rb:287:in `load'
    from /Users/alice/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activesupport-5.0.0.1/lib/active_support/dependencies.rb:287:in `block in load'
    from /Users/alice/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activesupport-5.0.0.1/lib/active_support/dependencies.rb:259:in `load_dependency'
    from /Users/alice/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activesupport-5.0.0.1/lib/active_support/dependencies.rb:287:in `load'
    from /Users/alice/.rbenv/versions/2.3.1/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:55:in `require'
    from /Users/alice/.rbenv/versions/2.3.1/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:55:in `require'
    from -e:1:in `<main>'

...但是回溯导致中止的回溯并不是很明显。

Answer 1

throw也接受可选的返回值，因此如果您需要知道触发(...) for link in links: if "career" in link.get("href") and 'COPENHAGEN' in link.text: print "<a href='%s'>%s</a>" %(link.get("href"), link.text)的回调，则可以使用该值。

throw（tag [，obj]）
将控制转移到等待throw的活动catch块的末尾。如果tag没有UncaughtThrowError块，则引发catch。可选的第二个参数提供tag块的返回值，否则默认为catch https://ruby-doc.org/core-2.4.1/Kernel.html#method-i-throw

例如：

nil

将返回def random_abort_1 if Random.rand(2) == 1 throw(:abort, __method__) end end。

确定在Rails 5中调用哪个回调throw（：abort）

1 个答案: