Once your model has its full_name attribute, you will have to configure permitted parameters for the #sign_up and #account_update Devise actions.
class ApplicationController < ActionController::Base
before_action :configure_devise_permitted_parameters, if: :devise_controller?
protected
def configure_devise_permitted_parameters
registration_params = [:full_name, :email, :password, :password_confirmation]
if params[:action] == 'update'
devise_parameter_sanitizer.for(:account_update) do
|u| u.permit(registration_params << :current_password)
end
elsif params[:action] == 'create'
devise_parameter_sanitizer.for(:sign_up) do
|u| u.permit(registration_params)
end
end
end
end