This group of articles describes how to define various forms in admin area utilizing the new API based on Symfony/Form and Vue.js view components.
Also, new API uses the DTO (Data-Transfer Object) approach, which is used to transport and validate data on its way to the entity and back. This allows to maintain several principles of a good architecture, such as Single Responsibility Principle.
You can start reading from Model editing page and proceed later to this guides:
The majority of entity editing pages in admin area use native X-Cart's approach for creating entity editing forms. It applies to category, order, user and other pages.
The approach described in this article applies to product details and settings pages.