Struct ProjectionUnit 

pub struct ProjectionUnit { /* private fields */ }

Standard composition of a Projector and a ReadModelStore.

This is the typical way to create a Projection: provide the event-handling logic (projector) and the storage backend (store), and ProjectionUnit wires them together.

Example

let projector = Box::new(UserListProjector);
let store: Arc<dyn ReadModelStore> = Arc::new(SqliteReadModelStore::new(pool));
let projection = ProjectionUnit::new(projector, store, "users_view");
engine.register(Box::new(projection));

Implementations

impl ProjectionUnit

pub fn new( projector: Box<dyn Projector>, store: Arc<dyn ReadModelStore>, table: impl Into<String>, ) -> Self

Create a new projection unit.

Arguments

• projector: The stateless event handler
• store: The read model storage backend
• table: Table/collection name to truncate on clear()

Trait Implementations

impl Projection for ProjectionUnit

fn name(&self) -> &str

Projection name (delegates to the projector).

fn handles(&self) -> Vec<String>

Event types this projection handles (delegates to the projector).

fn handle<'life0, 'life1, 'async_trait>( &'life0 self, event: &'life1 Event, ) -> Pin<Box<dyn Future<Output = ProjectionResult<()>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Handle a single event by applying it through the projector to the store.

fn clear<'life0, 'async_trait>( &'life0 self, ) -> Pin<Box<dyn Future<Output = ProjectionResult<()>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Clear all read model state for this projection.

fn rebuild<'life0, 'async_trait>( &'life0 self, events: Vec<Event>, ) -> Pin<Box<dyn Future<Output = ProjectionResult<()>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Rebuild from a set of events: clear, then replay matching events.