Snapshot

@rotorsoft/act-root

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@rotorsoft/act-root / act/src / Snapshot

Type Alias: Snapshot<TState, TEvents>

Snapshot<TState, TEvents> = object

Defined in: libs/act/src/types/action.ts:221

Snapshot of state at a specific point in time.

Snapshots represent the current state after applying events. They include metadata about how many events have been applied (patches) and how many snapshots have been taken for optimization.

Examples

const snapshot = await app.load(Counter, "counter-1");

console.log(snapshot.state);     // { count: 42 }
console.log(snapshot.patches);   // 8 (events since last snapshot)
console.log(snapshot.snaps);     // 1 (1 snapshot taken)
console.log(snapshot.event);     // Last event that created this snapshot

.on({ increment: z.object({ by: z.number() }) })
  .emit((action, snapshot) => {
    console.log("Current count:", snapshot.state.count);
    console.log("Events applied:", snapshot.patches);
    return ["Incremented", { amount: action.by }];
  })

Type Parameters

TState

TState extends Schema

State schema

TEvents

TEvents extends Schemas

Event schemas

Properties

event?

readonly optional event?: Committed<TEvents, keyof TEvents>

Defined in: libs/act/src/types/action.ts:225

Event that created this snapshot (undefined for initial state)

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patch?

readonly optional patch?: Readonly<Patch<TState>>

Defined in: libs/act/src/types/action.ts:231

Domain patch applied by this event (undefined for initial/loaded state)

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patches

readonly patches: number

Defined in: libs/act/src/types/action.ts:227

Number of patches applied since last snapshot

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snaps

readonly snaps: number

Defined in: libs/act/src/types/action.ts:229

Number of snapshots taken for this stream

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state

readonly state: TState

Defined in: libs/act/src/types/action.ts:223

Current state data