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docs(workflow): demonstrate Select in the purchase-order example #5378

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docs(workflow): demonstrate Select in the purchase-order example #5378

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19 changes: 14 additions & 5 deletions ...ontent/en/developing-applications/building-blocks/workflow/workflow-patterns.md
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Original file line number Diff line number Diff line change
Expand Up @@ -1277,17 +1277,26 @@ func PurchaseOrderWorkflow(ctx *workflow.WorkflowContext) (any, error) {
return "Auto-approved", nil
}
// Orders of $1000 or more require manager approval
if err := ctx.CallActivity(SendApprovalRequest, workflow.ActivityInput(order)).Await(nil); err != nil {
if err := ctx.CallActivity(SendApprovalRequest, workflow.WithActivityInput(order)).Await(nil); err != nil {
return "", err
}
// Approvals must be received within 24 hours or they will be cancelled
approvalEvent := ctx.WaitForExternalEvent("approval_received", time.Hour*24)
timeoutEvent := ctx.CreateTimer(time.Hour * 24)
winner, err := ctx.Select(approvalEvent, timeoutEvent)
if err != nil {
return "", err
}
if winner == 1 {
// The timer won the race: no approval arrived in time
return "Cancelled", nil
}
Comment on lines +1284 to +1293

@JoshVanL JoshVanL Oct 13, 2026

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I'm not sure that this Select example is the right one, since WaitForExternalEvent already have (and the same!) timeout. Is there another Select example we could do instead?

var approval Approval
if err := ctx.WaitForExternalEvent("approval_received", time.Hour*24).Await(&approval); err != nil {
// Assuming that a timeout has taken place - in any case; an error.
return "error/cancelled", err
if err := approvalEvent.Await(&approval); err != nil {
return "", err
}
// The order was approved
if err := ctx.CallActivity(PlaceOrder, workflow.ActivityInput(order)).Await(nil); err != nil {
if err := ctx.CallActivity(PlaceOrder, workflow.WithActivityInput(order)).Await(nil); err != nil {
return "", err
}
return fmt.Sprintf("Approved by %s", approval.Approver), nil
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