unset roles_mask column for cancancan gem in rails 4.2 -

i want set roles_mask integer column set roles of user.

here user model:

class user < activerecord::base      devise :database_authenticatable,     :recoverable, :rememberable, :trackable, :validatable      has_and_belongs_to_many :colleges     has_and_belongs_to_many :groups     has_and_belongs_to_many :pages     has_and_belongs_to_many :partners        roles = %w[admin college department news page ostad]      def roles=(roles)       roles = [*roles].map { |r| r.to_sym }       self.roles_mask = (roles & roles).map { |r| 2**roles.index(r)}.inject(0, :+)     end      def roles       roles.reject |r|          ((roles_mask.to_i || 0) & 2**roles.index(r)).zero?       end     end     scope :with_role, lambda { |role| {:conditions => "roles_mask & #{2**roles.index(role.to_s)} > 0 "} }      def role_symboles         roles.map(&:to_sym)     end      def has_role?(role)       roles.include?(role)     end end 

and user_params in user controller:

    def user_params       params.require(:user).permit(:name, :username, :roles, :email, :password, :password_confirmation, {:college_ids => [], :group_ids => [], :page_ids => [], :partner_ids => []})     end 

and here form:

<%= form_for(@user) |f| %>     .... <div class="row">   <div class="large-2 medium-2 small-12 columns">     <%= f.label t("admin.user.role") , class: "inline" %>   </div>   <div class="large-10 medium-10 small-12 columns">     <% role in user::roles %>       <span style="width:40px">         <%= check_box_tag "user[roles][#{role}]", role, @user.roles.include?(role), {:name => "user[roles][]"}%>         <%= label_tag "user_roles_#{role}", role.to_s.humanize %>       </span>     <% end %>     <%= hidden_field_tag "user[roles][]", nil %>   </div> </div> <% end %> 

and have roles_mask column in user model.

but when create user, , set columns, roles_mask column still null.