Class participant events

Class participant events describe an athlete’s participation in one Class. The subject is Classes/{classId}/Participants/{userId}. All three event types use the same enriched booking snapshot in data, including Class, trainer, cost, and UserSubscription context when available.

Event type	Meaning
`ClassParticipant.Created`	The athlete was added as a confirmed participant or placed in the queue.
`ClassParticipant.Updated`	Participation properties changed, including transitions between queue and confirmed states.
`ClassParticipant.Deleted`	The participation was removed; `data` contains its last saved snapshot.

See Class participants for booking rules, payments, attendance interpretation, and domain conflicts.

Common data contract

Booking properties:

Property	Meaning
`ClassId`, `UserId`	Composite identity of the participation.
`CreatedAtUtc`	Booking creation time; it also determines queue order.
`Mode`	`InSite` or `Remote`.
`State`	`Participant` for a confirmed place or `InQueue`.
`NoShow`	Current saved no-show flag. It is not proof of physical check-in.
`Trial`	Whether the participation is treated as a trial.
`ActorId`	UserId of the operation actor, or `null` when unavailable.

Class context:

Property	Meaning
`ClubId`	Club that owns the Class and scopes the event.
`ClassName`	Current Class name.
`ClassBegin`, `ClassEnd`	Complete Class interval as absolute instants.
`CalendarType`	`Club`, `PT`, or `Services`.
`ClassType`	`Course`, `Single`, or `Group`.
`TrainingType`	Activity classification associated with the Class.
`Location`	Class location, or `null`.
`TrainerId`, `TrainerName`	Assigned trainer identity when available.
`BookAsNoShow`	Whether the Class initially marks bookings as no-shows.

Payment and membership context:

Property	Meaning
`CreditsCost`	Credits associated with the booking. It is not a signed charge or refund for this event.
`SubscriptionCost`	Membership activities associated with the booking. It is not a signed balance change.
`TotalCredits`	Resulting credit balance when available; otherwise omitted.
`UserClassSubscriptionId`	UserSubscription assignment associated with the booking, or `null`.
`ClassSubscriptionId`, `SubscriptionName`, `SubscriptionType`	Product information, or `null` when unavailable.
`SubscriptionFrom`, `SubscriptionTo`	Assignment interval, or `null`.
`MaxActivities`	Assignment limit; `0` means unlimited, and `null` means no assignment data.
`AvailableActivities`	Remaining activities after the saved operation, or `null`.

A queued booking can reference a UserSubscription without having consumed an activity yet. Treat the event as a complete snapshot of the booking at that operation, not as a continuously updated view of the Class or membership.

ClassParticipant.Created

[
  {
    "id": "example-participant-created-event",
    "topic": "club-100001-events",
    "subject": "Classes/700001/Participants/300001",
    "data": {
      "ClubId": 100001,
      "ClassName": "Evening yoga",
      "ClassBegin": "2026-09-18T18:30:00+02:00",
      "ClassEnd": "2026-09-18T19:15:00+02:00",
      "CalendarType": "Club",
      "ClassType": "Group",
      "TrainingType": "Yoga",
      "Location": "Studio 1",
      "TrainerId": 800001,
      "TrainerName": "Example Trainer",
      "BookAsNoShow": false,
      "CreditsCost": 0,
      "SubscriptionCost": 1,
      "UserClassSubscriptionId": 600001,
      "ClassSubscriptionId": 500001,
      "SubscriptionName": "Monthly classes",
      "SubscriptionType": "Membership",
      "SubscriptionFrom": "2026-09-01T00:00:00+02:00",
      "SubscriptionTo": "2026-10-01T00:00:00+02:00",
      "MaxActivities": 10,
      "AvailableActivities": 9,
      "ClassId": 700001,
      "UserId": 300001,
      "CreatedAtUtc": "2026-09-18T09:12:25.980Z",
      "Mode": "InSite",
      "State": "Participant",
      "NoShow": false,
      "Trial": false,
      "ActorId": null,
      "TotalCredits": 99
    },
    "eventType": "ClassParticipant.Created",
    "eventTime": "2026-09-18T09:12:26.153Z",
    "dataVersion": "1.0"
  }
]

Creation does not guarantee a confirmed place: always inspect State, because a successful booking can create an InQueue entry.

ClassParticipant.Updated

An update uses the same complete data shape. Common cases include queue promotion, a change to Mode, NoShow, Trial, payment association, or another saved participation property.

Replace the local participation snapshot rather than inferring the transition from a previous event. Delivery can be duplicated or out of order, and no event is generated merely because a Class reaches its end time.

ClassParticipant.Deleted

The deletion event carries the last saved participation snapshot using the same shape. Costs remain the amounts associated with the removed booking. When provided, TotalCredits and AvailableActivities reflect the state after any refund.

Remove the record identified by ClassId plus UserId. The Class, athlete, and UserSubscription are not themselves deleted. Process the operation idempotently.

Recommended consumer flow

Deduplicate by envelope id.
Identify the participation by data.ClassId plus data.UserId.
Upsert the complete snapshot for Created and Updated.
Remove only that participation for Deleted.
Reconcile one known booking with GET /Classes/{classId}/Participants/{userId}.
Use GET /Classes/Bookings for paginated club-wide reconciliation, GET /Classes/{classId}/Bookings for one large Class, or the existing GET /Classes/{classId}/Participants array for a complete non-paginated Class refresh.