event-design

To design domain events for event-sourced .NET systems, create an abstract Event base class, use a generic Event<TData> wrapper with immutable IEventData records, and define EventType enum values to drive EF Core discriminators for consistent payload mapping.

Mapping domain events to EF Core requires registering concrete event types in the discriminator configuration using EventType enum values. This enum-driven approach avoids brittle string identifiers and ensures reliable polymorphic serialization.

Sequence tracking and versioning are required in event sourcing to enforce sequence ordering and support schema evolution. A Version field ensures safe event replays and prevents migration workflows from breaking when event data records change over time.

The best way to convert microservice commands to domain events is by using extension methods. This approach creates typed Event<TData> instances from commands, keeping the event payload explicit and ensuring the domain event hierarchy remains versionable.

String identifiers are not recommended for event discriminators in EF Core. Using EventType enum values prevents divergent event shapes and fragile serialization, ensuring robust event replay and migration workflows in event-sourced systems.

Handling collection-modification events in an event-sourced domain involves creating specific Event<TData> subclasses with their IEventData records. Add corresponding EventType enum values and register the concrete types in EF Core discriminator mappings.