Dev Tutorial: Adding Profile Update Feature with Event Sourcing in Sekiban DCB

A developer tutorial on the DEV Community platform walks through implementing a student profile update feature using Sekiban DCB, an event sourcing framework. The update allows changes to a student's name and maximum class limit, while keeping their ID and enrollment list intact. Rather than overwriting existing data, the system records a StudentProfileUpdated event, which a Projector then processes to rebuild the updated student state. A key validation rule prevents reducing the maximum class count below the student's current number of enrolled classes. The implementation follows a structured order covering Event, Decider, Command, Projector, and API layers, with sample code available on GitHub.