Struct EffectContext 

pub struct EffectContext {
    pub effect_id: Uuid,
    pub workflow: WorkflowRef,
    pub attempt: u32,
    pub created_at: OffsetDateTime,
}

Context provided to effect handlers during execution.

Contains metadata for correlation (routing results back to the workflow) and idempotency (safe retries with external services).

Idempotency

Use idempotency_key() when calling external APIs that support idempotency keys. The key is stable across retries but unique per effect instance.

Example

async fn handle(&self, effect: &MyEffect, ctx: &EffectContext) -> Result<Option<MyInput>, MyError> {
    // Use idempotency key for external API calls
    let result = self.payment_client
        .charge(amount, ctx.idempotency_key())
        .await?;

    // Use workflow_id for routing result back
    Ok(Some(MyInput::PaymentResult {
        order_id: ctx.workflow.workflow_id().to_string(),
        success: result.success,
    }))
}

Fields

effect_id: Uuid

Unique identifier for this effect instance (UUID v7).

Used as the correlation ID for tracking and routing.

workflow: WorkflowRef

The workflow this effect belongs to.

attempt: u32

Current attempt number (1-based).

First execution is attempt 1, first retry is attempt 2, etc.

created_at: OffsetDateTime

When this effect was first created/enqueued.

Implementations

impl EffectContext

pub fn new( effect_id: Uuid, workflow: WorkflowRef, attempt: u32, created_at: OffsetDateTime, ) -> Self

Create a new effect context.

pub fn idempotency_key(&self) -> String

Get the idempotency key for external service calls.

Format: {workflow_type}:{workflow_id}:{effect_id}

This key is:

• Stable across retries — same key for all attempts of the same effect
• Unique per effect — different effects have different keys

Use this when calling APIs that support idempotency keys (Stripe, etc.).

pub fn is_retry(&self) -> bool

Returns true if this is a retry (attempt > 1).

Trait Implementations

impl Clone for EffectContext

fn clone(&self) -> EffectContext

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for EffectContext

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.