Events

Events are a way to hook into Deepkit ORM and allow you to write powerful plugins. There are two categories of events: Query events and Unit-of-Work events. Plugin authors typically use both to support both ways of manipulating data.

Events are registered via Database.listen un an event token. Short-lived event listeners can also be registered on sessions.

import { Query, Database } from '@deepkit/orm';

const database = new Database(...);
database.listen(Query.onFetch, async (event) => {
});

const session = database.createSession();

//will only be executed for this particular session
session.eventDispatcher.listen(Query.onFetch, async (event) => {
});

Query Events

Query events are triggered when a query is executed via Database.query() or Session.query().

Each event has its own additional properties such as the type of entity, the query itself and the database session. You can override the query by setting a new query to Event.query.

import { Query, Database } from '@deepkit/orm';

const database = new Database(...);

const unsubscribe = database.listen(Query.onFetch, async event => {
    //overwrite the query of the user, so something else is executed.
    event.query = event.query.filterField('fieldName', 123);
});

//to delete the hook call unsubscribe
unsubscribe();

"Query" has several event tokens:

Unit Of Work Events

Unit-of-work events are triggered when a new session submits changes.