Error mass-assign

users_controller.rb

class UsersController < ApplicationController
  before_filter :set_user

  def edit
  end

  def update
    if @user.update_attributes(user_params)
      redirect_to root_path, notice: t('devise.registrations.updated')
    else
      render 'edit'
    end
  end

  private
    def set_user
      @user = User.find(params[:id])
    end

    def user_params
      params.require(:user).permit(:name, :gender, :last_donation, :blood_type)
    end
end