ruby-on-rails - 使用设计上下文的 "super"和 "super do |u|"之间的区别

Question

好吧，我想我得到了什么 super does独立的。基本上在设计中，如果 Users::RegistrationsController < Devise::RegistrationsController ，然后在任何行动中，都有一个 super将首先调用父级中相同命名操作的逻辑 Devise::RegistrationsController , 然后调用你写的内容。

换句话说...

class Devise::RegistrationsController
  def new
    puts "this is in the parent controller"
  end
end

class Users::RegistrationsController < Devise::RegistrationsController
  def new
    super
    puts "this is in the child controller"
  end
end

# Output if users#new is run would be:
# => "this is in the parent controller"
# => "this is in the child controller"

# If super were reversed, and the code looked like this
# class Users::RegistrationsController < Devise::RegistrationsController
  #  def new
    #  puts "this is in the child controller"
    #  super
  #  end
#  end
# Then output if users#new is run would be:
# => "this is in the child controller"
# => "this is in the parent controller"

我很好奇的是，我看到有人这样做:

class Users::RegistrationsController < Devise::RegistrationsController
  def new
    super do |user|
      puts "something"
    end
  end
end

我很难理解 do block 是什么正在完成。在我的例子中，在创建资源(用户)之后，我想对该资源(用户)调用一个额外的方法。

当前代码:

class Users::RegistrationsController < Devise::RegistrationsController
  def new
    super do |user|
      user.charge_and_save_customer
      puts user.inspect
    end
  end
end

我只是想知道这是否与做的有什么不同:

class Users::RegistrationsController < Devise::RegistrationsController
  def new
    super
    resource.charge_and_save_customer
    puts resource.inspect
  end
end

如果有帮助，我已经包含了父项 Devise::RegistrationsController代码如下:

def new
  build_resource({})
  set_minimum_password_length
  yield resource if block_given?
  respond_with self.resource
end

Answer 1

让我试着解释一下这里发生了什么:

class Users::RegistrationsController < Devise::RegistrationsController
  def new
    super do |user|
      user.charge_and_save_customer
      puts user.inspect
    end
  end
end

当您调用 super 时，您将返回到父 new 操作，因此现在将执行以下代码:

def new
  build_resource({})
  set_minimum_password_length
  yield resource if block_given?
  respond_with self.resource
end

但是等等...这里有一个yield，所以它将当前的resource yield给block，你可以把block想象成一个方法，它需要一个参数 (user)，这里的 resource (from parent) 将是参数:

# Here resource is assigned to user
user.charge_and_save_customer
puts user.inspect

现在，由于 block 已完全执行，它将再次开始执行 super :

respond_with self.resource