NautilusTrader
ConceptsEvents
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OrderPendingUpdate

OrderPendingUpdate represents a ModifyOrder command having been sent to the trading venue. The ExecutionEngine applies it to the order, updates the Cache, and publishes it on the MessageBus. It fires when the system dispatches a modify request and awaits venue acknowledgement.

Typical transition: ACCEPTED -> PENDING_UPDATE. Handler: on_order_pending_update.

Fields

Beyond the common Python order event fields, OrderPendingUpdate carries:

FieldPython typeRequired/defaultDescription
venue_order_idVenueOrderId or NoneNoneThe venue‑assigned order identifier, if known.
account_idAccountId or NoneRequiredThe account associated with the order, if known.
reconciliationboolRequiredIf generated during reconciliation.

Example

Reading the event in a strategy handler:

def on_order_pending_update(self, event: OrderPendingUpdate) -> None:
    self.log.info(f"Modify pending for {event.client_order_id}")
  • Events - Event categories, dispatch, and the common order event fields.
  • Orders - Order types and the state machine.

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