Primitive Input Types for Business Logic Entry Points

Goal

The fields of command and query types accepted by business-logic entry points must use only primitive or basic types.

A business-logic entry point receives raw input data and is responsible for constructing, loading, or looking up domain entities internally. The caller must never be required to build a domain entity before calling the entry point.

Do not use domain-entity types, domain aggregate types, value objects with behavior, or other complex domain objects as fields in command or query types.

What Counts as In Scope

Apply this skill to code that does one or more of these things:

• defines a ...Command or ...Query type for a business-logic entry point
• defines the fields of an entry-point input type
• passes a domain entity or domain aggregate as a field of a command or query type
• uses a complex domain object where a primitive or basic type would suffice