Cancan Ability

In your gemfile Include.

1. gem "cancan" 

2. install bundle. 

3. rails g cancan:ability

this will generate an ability class in your models. 

define your Abilities there like below.

but keep remember that you have already defined roles, 

such as you have a User model,

having two roles defined i.e admin and support.

class Ability

include CanCan::Ability

def initialize(user)

user||= User.new

can :read, :all

if user.role == 'admin'

can :manage, :all

else

can :read, :all

end

end

end

4. the resource on which you want to restrict a user,
 use the following filter in their controller.

                  load_and_authorize_resource

5. if you want restrict something in the views not to show.

<% if can? :manage, @flower %>

<td><%= link_to 'Edit', edit_flower_path(flower) %></td>

<% end %>

<% if can? :manage, @flower %>

<td><%= link_to 'Destroy', flower_path(flower),

method: :delete, data: { confirm: 'Are you sure?' } %></td>

<% end %>