Configuration

Event Nest has one persistence module per adapter. Each module builds and exports an event store under the EVENT_STORE injection token. Snapshot storage is configured by each adapter; there is no shared public snapshot module-options type.

Registration methods

All adapters expose the same four static methods.

Method	Scope	Options resolution	Result
`forRoot(options)`	Global	Synchronous object	`EVENT_STORE` is available application-wide after one import.
`forRootAsync(options)`	Global	Factory returning an object or promise	Same global export, after the factory resolves.
`register(options)`	Scoped	Synchronous object	`EVENT_STORE` is available only to the importing module and modules that re-export it.
`registerAsync(options)`	Scoped	Factory returning an object or promise	Same scoped export, after the factory resolves.

The corresponding modules are EventNestMongoDbModule, EventNestPostgreSQLModule, and EventNestMSSQLModule. Registration exports only EVENT_STORE; adapter clients, snapshot stores, schema configuration, and emitters are implementation providers, not module exports.

Each asynchronous options type has this shape:

Adapter	Async type	Factory result
MongoDB	`MongoDbModuleAsyncOptions`	`MongodbModuleOptions \| Promise<MongodbModuleOptions>`
PostgreSQL	`PostgreSQLModuleAsyncOptions`	`PostgreSQLModuleOptions \| Promise<PostgreSQLModuleOptions>`
Microsoft SQL Server	`MSSQLModuleAsyncOptions`	`MSSQLModuleOptions \| Promise<MSSQLModuleOptions>`

Option	Type	Required	Default	Description
`useFactory`	`(...parameters: any[]) => Options \| Promise<Options>`	Yes	None	Produces that adapter's complete module options.
`inject`	`any[]`	No	`undefined`	Tokens passed to `useFactory` in order. The async options types do not have an `imports` property, so dependencies must already be visible in the module context.

EventNestPostgreSQLModule.forRootAsync({
    inject: [ConfigService],
    useFactory: (config: ConfigService) => ({
        aggregatesTableName: "aggregates",
        connectionUri: config.getOrThrow("DATABASE_URL"),
        eventsTableName: "events",
        schemaName: "event_nest"
    })
})

Shared option

CoreModuleOptions contributes one option to every adapter.

Option	Type	Required	Event Nest default	Description
`concurrentSubscriptions`	`boolean`	No	`false`	`false` dispatches emitted events in order. `true` dispatches event-handler work concurrently. See subscription behavior .

MongoDB

Install @event-nest/core, @event-nest/mongodb, and its mongodb 7.x peer dependency.

`MongodbModuleOptions`

Option	Type	Required	Event Nest default	Description
`aggregatesCollection`	`string`	Yes	None	Collection holding aggregate IDs and current versions.
`connectionUri`	`string`	Yes	None	URI passed as the first `MongoClient` constructor argument.
`eventsCollection`	`string`	Yes	None	Collection holding persisted events.
`mongoClientConfiguration`	`MongoClientOptions`	No	`undefined`	Passed unchanged as the second `MongoClient` constructor argument. Driver defaults apply when omitted.
`concurrentSubscriptions`	`boolean`	No	`false`	Shared subscription dispatch option.
`snapshotCollection`	`string`	Conditional	Snapshots disabled	Snapshot collection. Must be supplied together with `snapshotStrategy`.
`snapshotStrategy`	`SnapshotStrategy`	Conditional	Snapshots disabled	Snapshot creation policy. Must be supplied together with `snapshotCollection`.

The options type is a union: omit both snapshot fields to use NoOpSnapshotStore, or provide both. The provider repeats this check at runtime and throws To use snapshots, both 'snapshotStrategy' and 'snapshotCollection' must be provided. for an incomplete pair.

MongoDB saves and purges with transactions. Use a deployment that supports transactions, such as a replica set or sharded cluster; a standalone server cannot complete those operations.

PostgreSQL

Install @event-nest/core, @event-nest/postgresql, and its pg peer dependency (^8.14.1).

`PostgreSQLModuleOptions`

Option	Type	Required	Event Nest default	Description
`aggregatesTableName`	`string`	Yes	None	Aggregate-version table name.
`connectionUri`	`string`	Yes	None	PostgreSQL connection string passed to Knex.
`eventsTableName`	`string`	Yes	None	Event table name.
`schemaName`	`string`	Yes	None	Schema prepended to configured table names. The schema itself is not created.
`connectionPool`	`ConnectionPoolOptions`	No	`undefined`	Passed to Knex as `pool`; Knex/Tarn defaults apply when omitted.
`ensureTablesExist`	`boolean`	No	`false`	Checks for and creates missing aggregate, event, and configured snapshot tables during application bootstrap. Requires DDL permission.
`ssl`	`SslOptions`	No	SSL object omitted	When supplied, maps `certificate` to `ssl.ca` and forwards `rejectUnauthorized`.
`concurrentSubscriptions`	`boolean`	No	`false`	Shared subscription dispatch option.
`snapshotTableName`	`string`	Conditional	Snapshots disabled	Snapshot table name. Must be supplied together with `snapshotStrategy`.
`snapshotStrategy`	`SnapshotStrategy`	Conditional	Snapshots disabled	Snapshot creation policy. Must be supplied together with `snapshotTableName`.

An incomplete snapshot pair throws To use snapshots, both 'snapshotStrategy' and 'snapshotTableName' must be provided. When both fields are absent, Event Nest installs NoOpSnapshotStore.

`SslOptions`

Option	Type	Required	Event Nest default	Description
`rejectUnauthorized`	`boolean`	Yes	None	Forwarded to the PostgreSQL driver's SSL configuration.
`certificate`	`string`	No	`undefined`	CA certificate text forwarded as `ssl.ca`.

Omitting ssl does not force an SSL setting; the connection consists only of connectionString. Supplying ssl creates an SSL object even when certificate is omitted.

PostgreSQL `ConnectionPoolOptions`

All fields are optional and passed through to Knex/Tarn. Event Nest assigns no PostgreSQL pool defaults.

Option	Type	Description
`acquireTimeoutMillis`	`number`	Maximum wait when acquiring a resource.
`afterCreate`	`Function`	Hook run after a connection is created.
`createRetryIntervalMillis`	`number`	Delay between create retries.
`createTimeoutMillis`	`number`	Connection creation timeout.
`destroyTimeoutMillis`	`number`	Resource destruction timeout.
`idleTimeoutMillis`	`number`	Idle lifetime before reaping.
`log`	`(message: string, logLevel: string) => void`	Pool log callback.
`max`	`number`	Maximum pool size.
`min`	`number`	Minimum pool size.
`name`	`string`	Pool name.
`priorityRange`	`number`	Number of priority levels.
`propagateCreateError`	`boolean`	Whether creation errors are propagated immediately.
`reapIntervalMillis`	`number`	Interval between idle-resource checks.
`refreshIdle`	`boolean`	Whether idle resources are refreshed.
`returnToHead`	`boolean`	Whether released resources return to the head of the free list.

Microsoft SQL Server

Install @event-nest/core, @event-nest/mssql, and its tedious 20.x peer dependency. Event Nest uses Knex's mssql client internally.

`MSSQLModuleOptions`

Option	Type	Required	Event Nest default	Description
`aggregatesTableName`	`string`	Yes	None	Aggregate-version table name.
`connection`	`MSSQLConnectionOptions`	Yes	None	Structured SQL Server connection settings.
`eventsTableName`	`string`	Yes	None	Event table name.
`schemaName`	`string`	Yes	None	SQL Server schema, commonly `dbo`. The schema itself is not created.
`connectionPool`	`ConnectionPoolOptions`	No	`{ min: 0 }` plus Knex/Tarn defaults	Pool settings merged over Event Nest's `min: 0`.
`ensureTablesExist`	`boolean`	No	`false`	Creates missing aggregate, event, and configured snapshot tables at bootstrap. Requires DDL permission.
`concurrentSubscriptions`	`boolean`	No	`false`	Shared subscription dispatch option.
`snapshotTableName`	`string`	Conditional	Snapshots disabled	Snapshot table name. Must be supplied together with `snapshotStrategy`.
`snapshotStrategy`	`SnapshotStrategy`	Conditional	Snapshots disabled	Snapshot creation policy. Must be supplied together with `snapshotTableName`.

SQL Server validates schemaName, aggregatesTableName, eventsTableName, and, when present, snapshotTableName. Each must be non-empty, at most 128 characters, and contain no dot. Supply schema and table separately.

`MSSQLConnectionOptions`

Option	Type	Required	Event Nest default	Description
`database`	`string`	Yes	None	Database name.
`password`	`string`	Yes	None	Login password.
`server`	`string`	Yes	None	SQL Server host.
`user`	`string`	Yes	None	Login user.
`connectionTimeout`	`number`	No	Driver default	Forwarded to the connection.
`encrypt`	`boolean`	No	`true`	Tedious encryption option.
`instanceName`	`string`	No	`undefined`	Named instance. Mutually exclusive with `port`.
`port`	`number`	No	Driver default	TCP port. Mutually exclusive with `instanceName`.
`requestTimeout`	`number`	No	Driver default	Request timeout.
`serverName`	`string`	No	`undefined`	TLS server name forwarded to Tedious.
`trustServerCertificate`	`boolean`	No	`false`	Whether to trust the server certificate without validation.

Event Nest also fixes lowerCaseGuids: true and useUTC: true, and binds JavaScript Date values as DateTime2. Configuring both port and instanceName throws MSSQL connection options cannot provide both 'port' and 'instanceName'.

SQL Server `ConnectionPoolOptions`

Every field is optional. Event Nest merges this object over { min: 0 }; a provided min overrides it, and all remaining defaults belong to Knex/Tarn.

Option	Type	Description
`acquireTimeoutMillis`	`number`	Maximum wait when acquiring a resource.
`afterCreate`	`Function`	Hook run after a connection is created.
`createRetryIntervalMillis`	`number`	Delay between create retries.
`createTimeoutMillis`	`number`	Connection creation timeout.
`destroyTimeoutMillis`	`number`	Resource destruction timeout.
`idleTimeoutMillis`	`number`	Idle lifetime before reaping.
`log`	`(message: string, logLevel: string) => void`	Pool log callback.
`max`	`number`	Maximum pool size.
`min`	`number`	Minimum pool size; Event Nest defaults this field to `0`.
`name`	`string`	Pool name.
`priorityRange`	`number`	Number of priority levels.
`propagateCreateError`	`boolean`	Whether creation errors are propagated immediately.
`reapIntervalMillis`	`number`	Interval between idle-resource checks.
`refreshIdle`	`boolean`	Whether idle resources are refreshed.
`returnToHead`	`boolean`	Whether released resources return to the head of the free list.

Snapshot option dependency

Snapshot support always has three independent requirements:

Configure the adapter's strategy and storage location as a pair.
Add snapshotRevision to @AggregateRootConfig on every aggregate that can match the strategy.
Implement callable toSnapshot() and applySnapshot() methods on those aggregate instances.

The adapter-specific location field is part of its public options. No shared SnapshotsEnabled or SnapshotsDisabled type is exported. See decorators and common snapshot problems .

Sources

Found a documentation problem? Report an issue

Edit this page

Last update at: 2026/09/02 00:14

On this page

Registration methods Shared option MongoDB MongodbModuleOptions PostgreSQL PostgreSQLModuleOptions SslOptions PostgreSQL ConnectionPoolOptions Microsoft SQL Server MSSQLModuleOptions MSSQLConnectionOptions SQL Server ConnectionPoolOptions Snapshot option dependency Sources