Installation
This library consists of a core module @ocoda/event-sourcing that provides the building blocks and can be complemented with an integration library for setting up a persistence layer for your events using a specific database provider.
By default the core library will use an in-memory event- and snapshot-store, which is useful for testing and prototyping, but not recommended for production use.
Setting up the module
Basic setup
For setting up the module you need to import the EventSourcingModule and configure it.
For the basic setup you only need to provide the events array, an array of event classes that are used to define the events.
While this great for testing and prototyping, you won't be able to persist the events and snapshots. If you require persistence skip to the advanced setup.
import { Module } from '@nestjs/common';
import { EventSourcingModule } from '@ocoda/event-sourcing';
import {
AccountOpenedEvent,
AccountCreditedEvent,
AccountDebitedEvent,
AccountClosedEvent,
} from './app.providers';
@Module({
imports: [
EventSourcingModule.forRoot({
events: [
AccountOpenedEvent,
AccountCreditedEvent,
AccountDebitedEvent,
AccountClosedEvent,
],
}),
],
})
export class AppModule {}Advanced setup
If you want to use a specific database provider for event- and snapshot-persistence you need to provide the eventStore and snapshotStore configuration.
Each integration library comes with a driver and interface to indicate which parameters are required for connecting to the specified store.
import { Events } from './app.providers';
import { PostgresEventStore, type PostgresEventStoreConfig } from '@ocoda/event-sourcing-postgres';
import { MongoDBSnapshotStore, type MongoDBSnapshotStoreConfig } from '@ocoda/event-sourcing-mongodb';
@Module({
imports: [
EventSourcingModule.forRootAsync<PostgresEventStoreConfig, MongoDBSnapshotStoreConfig>({
useFactory: () => ({
events: Events,
eventStore: {
driver: PostgresEventStore,
host: '<URL>',
port: 5432,
user: '<username>',
password: '<password>',
database: '<database>',
},
snapshotStore: {
driver: MongoDBSnapshotStore,
url: '<URL>',
},
}),
}),
],
})
export class AppModule {}