Command handlers convert commands into events

In event sourcing and CQRS, command handlers should take the commands and turn it into one or more events.

Of course, it also needs to validate commands, not emitting an event as an event holds actual change.

Reference

Hoffman, Kevin. Real-World Event Sourcing: Distribute, Evolve, and Scale Your Elixir Applications. The Pragmatic Bookshelf, 2025. The Pragmatic Programmers.

Highlights or timestamps

Real-World Event Sourcing

The purpose of a command handler is essentially to convert a command into one or more events.

— highlight from Highlights of Real-World Event Sourcing