tap/app/controllers/application_controller.rb

class ApplicationController < ActionController::Base
  # Prevent CSRF attacks by raising an exception.
  # For APIs, you may want to use :null_session instead.
  protect_from_forgery with: :exception
  before_action :configure_permitted_parameters, if: :devise_controller?

  rescue_from CanCan::AccessDenied do |exception|
    redirect_to root_path, flash: { error: exception.message }
  end

  def after_sign_in_path_for(resource)
    root_path
  end

  def after_sign_up_path_for(resource)
    root_path
  end

  protected

  def configure_permitted_parameters
    devise_parameter_sanitizer.for(:sign_up) { |u| u.permit(
      :nickname, :password, :password_confirmation,
      :avatar
    ) }

    devise_parameter_sanitizer.for(:account_update) { |u| u.permit(
      :password, :password_confirmation, :current_password, :avatar
    ) }
  end
end