how to execute an action if the before_action returns false

问题

I know that with the following code:

before_action :signed_in?, only: [:new]

the action new will be executed if the signed_in? returns true, but instead if I want the new action to be executed when signed_in? returns false what do I have to do? Do I have to create a new method called, for instance, not_signed_in??

Here it is my signed_in? method

def signed_in?
  !@current_user.nil?
end

回答1:

before_action doesn't work as you think - it doesn't prevent action to be executed if callback returns false. I would solve your problem in a little bit different manner, for example:

before_action :redirect_to_root, :if => :signed_in?, :only => :new

# ...
private
def redirect_to_root
  redirect_to root_path
end

回答2:

before_action :new, unless: -> { signed_in? }

alltough i think its better to redirect in the action which was called.

def your_action_called
  redirect_to :new unless signed_in?
  [...code ...]
end

回答3:

If you want to cover all other methods with
before_action :signed_in?
except new action, you'b better to use :except instead of :only
like this:
before_action :signed_in?, except: :new

来源：https://stackoverflow.com/questions/20120485/how-to-execute-an-action-if-the-before-action-returns-false