Aggregate store

Eventuous provides a number of extensions for IEventReader and IEventWriter interfaces for aggregate persistence.

Storing aggregates

Storing an aggregate instance implies appending new events from the list of changes to the aggregate stream. Functions that allow that are listed below. All those are extensions to IEventWriter interface.

Using stream name

This function requires a pre-calculated stream name to be provided, so it doesn’t use any convention for resolving stream names. It uses the provided stream name as-is.

Task<AppendEventsResult> IEventWriter.StoreAggregate<TAggregate, TState>(
    StreamName        streamName,
    TAggregate        aggregate,
    AmendEvent?       amendEvent        = null,
    CancellationToken cancellationToken = default
)

Parameter	Type	Description
`streamName`	`StreamName`	Aggregate stream name
`aggregate`	`TAggregate<TState>`	Aggregate instance
`amendEvent`	`Func<StreamEvent, StreamEvent>`	Function that allows adding things like custom metadata
`cancellationToken`	`CancellationToken`	Cancellation token

Using explicit aggregate id

This function uses the stream name map to convert the provided aggregate identity to a stream name. If the stream name map is not supplied, it will use the default, convention-based calculation (TypeName-Id).

Task<AppendEventsResult> IEventWriter.StoreAggregate<TAggregate, TState, TId>(
    TAggregate        aggregate,
    TId               id,
    StreamNameMap?    streamNameMap     = null,
    AmendEvent?       amendEvent        = null,
    CancellationToken cancellationToken = default
)

Parameter	Type	Description
`aggregate`	`TAggregate<TState>`	Aggregate instance
`id`	`TId`	Aggregate identity
`streamNameMap`	`StreamNameMap`	Map between identities and stream names
`amendEvent`	`Func<StreamEvent, StreamEvent>`	Function that allows adding things like custom metadata
`cancellationToken`	`CancellationToken`	Cancellation token

Using aggregate identity from state

This function supports storing aggregates with identity-aware state (State<TId>) and uses the aggregate State.Id property combined with the stream name map to resolve the stream name. If the stream name map is not supplied, it will use convention-based stream name calculation.

Task<AppendEventsResult> IEventWriter.StoreAggregate<TAggregate, TState, TId>(
    TAggregate        aggregate,
    StreamNameMap?    streamNameMap     = null,
    AmendEvent?       amendEvent        = null,
    CancellationToken cancellationToken = default
)

Parameter	Type	Description
`aggregate`	`TAggregate<TState, TId>`	Aggregate instance
`streamNameMap`	`StreamNameMap`	Map between identities and stream names
`amendEvent`	`Func<StreamEvent, StreamEvent>`	Function that allows adding things like custom metadata
`cancellationToken`	`CancellationToken`	Cancellation token

Loading aggregates

Several extensions for IEventReader interface allow loading aggregates from an event store.

Using stream name

This function requires a pre-calculated stream name to be provided, so it doesn’t use any convention for resolving stream names. It uses the provided stream name as-is.

Task<TAggregate> LoadAggregate<TAggregate, TState>(
    StreamName                streamName,
    bool                      failIfNotFound    = true,
    AggregateFactoryRegistry? factoryRegistry   = null,
    CancellationToken         cancellationToken = default
)

Parameter	Type	Description
`streamName`	`StreamName`	Aggregate stream name
`failIfNotFound`	`bool`	When set to `true`, the function will throw an `AggregateNotFound` exception if the stream cannot be found. Otherwise, it will return a new aggregate instance.
`factoryRegistry`	`AggregateFactoryRegistry`	Optional aggregate factory registry, which is used to create new aggregate instances. If not supplied, the default registry is used.
`cancellationToken`	`CancellationToken`	Cancellation token

Using aggregate id

Task<TAggregate> IEventWriter.LoadAggregate<TAggregate, TState, TId>(
    TId                       aggregateId,
    StreamNameMap?            streamNameMap     = null,
    bool                      failIfNotFound    = true,
    AggregateFactoryRegistry? factoryRegistry   = null,
    CancellationToken         cancellationToken = default
)

Parameter	Type	Description
`id`	`TId`	Aggregate identity
`streamNameMap`	`StreamNameMap`	Map between identities and stream names
`failIfNotFound`	`bool`	When set to `true`, the function will throw an `AggregateNotFound` exception if the stream cannot be found. Otherwise, it will return a new aggregate instance.
`factoryRegistry`	`AggregateFactoryRegistry`	Optional aggregate factory registry, which is used to create new aggregate instances. If not supplied, the default registry is used.
`cancellationToken`	`CancellationToken`	Cancellation token

Aggregate store

Storing aggregates

Using stream name

Using explicit aggregate id

Using aggregate identity from state

Loading aggregates

Using stream name

Using aggregate id

Multi-tier store