Question

I want to protect a specific page in a controller from access only if the user is logged in it is the add.html page for adding questions, the index.html page is used to show questions that are asked but I want to to remain public. How do I make it that when someone clicks on ask a question from index that it checks for login and if not logged in has flash notice saying you must login and redirect at same time to login page.

New error on index page:

NoMethodError in Car#index

Showing app/views/car/index.html.erb where line #3 raised:

You have a nil object when you didn't expect it!
You might have expected an instance of Array.
The error occurred while evaluating nil.each
Extracted source (around line #3):

1: <h2>Current List of Open Questions</h2>
2: <dl>
3: <% @car.each do |car| %>
4:   <dd>
5:     <%= car.name %><br />
6:     <%= car.description %><br />

Answer 1

You want to add a before_filter to ensure the user is logged in before running the protected actions. Here’s a simple example – naturally your implementation details depend on how you rolled your own auth.

In your application controller (assuming you’re storing the id of the current logged in user in session[:user_id]):

class ApplicationController < ActionController::Base
  protected
  def ensure_login
    if session[:user_id].blank?
      flash[:notice] = 'You must be logged in to use this part of the site.'
      begin
        redirect_to :back
      rescue
        redirect_to '/'
      end
      return false
    end
  end
end

and then in the controller where you are limiting access:

class QuestionsController < ApplicationController
  before_filter :ensure_login, :only => [ :add ]
end