Simplify validation in domain

[mttschltz]

Problem

Validation in the domain isn't easy to maintain

• On creation, class-validator decorators validate simple properties
• Custom validators validate complex (interface) properties
  • The current implementation of this is weak as it uses the (below mentioned) type guard, which only checks property existence. However, it may be a reasonable assumption that at runtime all such interfaces were created from factory functions and thus are valid anyway
• A type guard validates the type

Ideally the entity could have its structure and type validated in one place.

[mttschltz]

The current implementation of this is weak as it uses the (below mentioned) type guard, which only checks property existence.

One idea to improve this is to use recursion. E.g. the custom validator uses the factory function to construct an entity from a class. The entity would then be validated.

Though could this lead to an infinite loop? E.g. a child validates a parent, which validates it's children, and so on.

However, it may be a reasonable assumption that at runtime all such interfaces were created from factory functions and thus are valid anyway

Maybe this is enough after all.