event.store_required: An action emits an event but writes no database, and the app names no database to keep its events in

An action emits an event but writes no database, and the app names no database to keep its events in.

Area 12, Background work; not declinable; the next step is usually the human's.

Why Jadpo refuses it

An event waits in an outbox, a table in a database, until each of its subscribers has it. It is written in the same transaction as the action's own writes, so it is delivered only if they commit. An action that writes no database has no transaction to put it in, and Jadpo won't choose a database for it: application { events: { store: } } names the one that keeps such events, even when the action reads another.

What it looks like

main.jadpo:

example

type Note = Text {    max_length: 200}type NoteSeen = Event {    note: Note}action glance(note: Note) -> Unit {    emit NoteSeen {        note: note    }}

jadpo checkcheck failed: 1 error, 1 file

error glance emits NoteSeen but writes no store to keep it in

--> main.jadpo:10:5

   |10 |     emit NoteSeen {   |     ^^^^^^^^^^^^^^^ no outbox

reason: An event is kept in the outbox of the store its action writes, in the same transaction, until its subscribers have it; glance writes no store, itself or through what it calls, and app.jadpo names none with events: { store: }.
next: Add events: { store: main } to application { } in app.jadpo (human)
rule: event.store_required
help: https://jadpo.dev/docs/errors/event.store_required

(human) at the end of the next: line tells your coding agent to stop and ask you which fix you want, because the choice is yours to make: it decides which database keeps the events of actions that write none.

How to fix it

If a database should keep these events, name it in events: { store: } in app.jadpo. A single file has no app.jadpo, so here the example is a project, with glance in a notes domain and one database, main. In app.jadpo:

example

    events: {        store: main    }

glance now begins a transaction in main for its events, and each NoteSeen waits in main's outbox until its subscribers have it. Every other action that emits and writes no database keeps its events there too.

An action that writes a database keeps its events in that one instead, in the same transaction, so it never needs events: { store: }.

Why Jadpo refuses it

What it looks like

How to fix it

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