Rails在Controller中建模方法可用性

Question

I have a method in my model which should detect the User Agent. How can I make it available to all my controller methods?

Model:

  def is_iphone_request?
       if request.user_agent =~ /iPhone/
       return true
     end
  end

Controller (throws an error):

def index
  @user_agent = is_iphone_request?
end

How can I achieve this? Any help is much appreciated.

Answer 1

将方法放在ApplicationController而不是模型中。

Answer 2

I'm not sure why you've put the request user-agent check on the model--it seems like a controller centric behavior. And there is a request attribute IN a controller that you can use.

Answer 3

Though request will not be available in the model (you will get a NameError with the following code), your current problem is that the controller is throwing a NoMethodError because you are missing self. on the method definition. Make it a class method (by adding self. ):

class MyModel < ActiveRecord::Base
  def self.is_iphone_request?
   if request.user_agent =~ /iPhone/
     return true
   end
end

Then, in your controller, you can use:

MyModel.is_iphone_request?

But like I said, you will get a NameError because request is not available in the model.

Your method is_iphone_request? should probably live in your ApplicationController (where it can be a regular private method). You can also trim it down:

class ApplicationController < ActionController::Base
  ...
  private
  def is_iphone_request?
    request.user_agent =~ /iPhone/ ? true : false
  end
end

Then, in your controller, you can use:

is_iphone_request?