Implement role authorization

app/controllers/admin/contacts_controller.rb

@@ -1,33 +1,30 @@
 module Admin
   class ContactsController < ApplicationController
-    before_action :set_conference
-    before_action :set_conference
-    before_action :set_contact, only: [:edit, :update]
+  load_and_authorize_resource :conference, find_by: :short_title
+  load_and_authorize_resource through: :conference, singleton: true
 
-    # GET /:conference/contact/edit
-    def edit
+  # GET /:conference/contact
+  def show; end
+
+  # GET /:conference/contact/edit
+  def edit; end
+
+  # PATCH/PUT /:conference/contact
+  def update
+    if @contact.update(contact_params)
+      redirect_to admin_conference_contact_path, notice: 'Contact details were successfully updated.'
+    else
+      render :edit
     end
+  end
 
-    # PATCH/PUT /:conference/contact
-    def update
-      if @contact.update(contact_params)
-        redirect_to edit_admin_conference_contact_path, notice: 'Contact details were successfully updated.'
-      else
-        render :edit
-      end
-    end
-
-    private
-
-    # Use callbacks to share common setup or constraints between actions.
-    def set_contact
-      @contact = @conference.contact
-    end
-
-    def set_conference
-      @conference = Conference.find_by(short_title: params[:conference_id])
-    end
+  # DELETE /:conference/contact
+  def destroy
+    @contact.destroy
+    redirect_to admin_conference_contacts_url, notice: 'Contact details were successfully destroyed.'
+  end
 
+  private
     # Only allow a trusted parameter "white list" through.
     def contact_params
       # params.require(:contact).permit(:social_tag, :email, :facebook, :googleplus, :twitter, :instagram, :public)