Rename an event

This guide shows you how to rename an event class and keep its stored events readable.

Every stored event keeps the name it was written under, such as cart.item_added. A rename changes the conventional name, so stored events have no class to read into. Deedbox fails at start-up in that case, with DBX016, and names the likely rename.

Keep the old name as an alias

public record LineAdded(string Sku, int Qty);             // was called ItemAdded

public record ItemAddedV2(string Sku, int Qty);           // the old shape, kept for the typed upcaster

public record ItemPriced(string Sku, int Qty, decimal Price);

services.AddDeedbox(es => es
    .UsePostgres(connStr)
    .Stream<Cart>(s => s
        .Event<LineAdded>(e => e.Alias("cart.item_added")) // stored events keep their old name
        .Event<CheckedOut>()));

New events are stored under the new name, cart.line_added. Stored events under cart.item_added read as LineAdded.

To keep the old name for new events too, set it explicitly instead: .Event<LineAdded>(name: "cart.item_added").

Let CI catch it first

The event contract lockfile fails a test when a name disappears without an alias.