What exactly filter is ?
Filter is a simple method which is executed “before” / “after” / “around” a controller action.
For example, one filter might check if the user has the credentials for accessing a particular action in a controller.
Where can I place my filter ?
Filters are inherited so if you a place filter in “application_controll.rb” file then it will be applicable to every controllers in application.
Step – 1
Create a method ( in application_controller.rb file) :
flash[:notice] = "Sorry, login before you continue !!! "
redirect_to :controller => "user_sessions", :action => "new"
Step – 2
Use the method in application_controller as a filter :
Now write the before_filter block in the controller where you want to restrict unauthorized users.
You can also restrict particular action of a controller by writing the action name.
class UsersController < ApplicationController #as controller is inherited from ApplicationController hence filter is accessible here.
before_filter :check_user_login_in, :only => [:profile]
#this line is important
[ Your block of code to render your profile page ]
In the above block the “before_filter” restrict the non-registered user to access the profile page and redirect them to login page.
We can also restrict multiple actions by writing like this :
before_filter :user_logged_in, :only => [:profile, :edit]
In this case the filter is applied to only these two methods of a particular controller :
before_filter :user_logged_in, :except => [:index, :show]
in this case filter is applied to all the other actions except index and show action of a particular controller.
if a filtration action fails then respective controller action won’t get exectued and the further scheduled filters are also get cancelled.