dto-schema-design

To design DTO schemas that prevent mass assignment, enforce strict request schemas with additionalProperties false and use explicit field allowlists for DTO-to-domain mapping. This ensures validation occurs before domain logic and internal models never leak to API layers.

Handling null vs absent field semantics in API contracts requires documenting four-state behavior (null, absent, empty, present) within versioned DTO schemas. This explicitly defines field types and nullability to preserve forward-backward compatibility across HTTP and gRPC payloads.

To evolve API contracts without breaking clients, apply additive-only minor evolution rules to versioned DTO schemas. This decouples external API shapes from internal domain models while preserving compatibility for request and response bodies.

You need strict DTO schemas with additionalProperties false for request validation when building HTTP or gRPC APIs that must reject unknown fields. This guardrail prevents mass assignment vulnerabilities and ensures only explicitly defined fields enter domain logic.

Yes, explicit DTO-to-domain mapping applies to CQRS view projections and event payloads by using assemblers, converters, and mappers. This decouples external transfer shapes from internal persistence models while enforcing validation and nullability semantics.

Relying solely on internal domain models for API responses causes internal model leakage and client breakage during model changes. Without explicit versioned DTO contracts, you lose forward-backward compatibility and expose mass assignment security risks.