> ## Documentation Index
> Fetch the complete documentation index at: https://replyke-feat-push-rich-payload-fields.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Set RSVP

> Set or change the caller's RSVP to an event

Sets or changes the caller's RSVP. A new RSVP is created, or an existing one is switched, and the event's `rsvpCounts` are updated atomically. Requires authentication, and the caller must be able to [see the event](/data-models/event#visibility) (otherwise `404`).

Transitions into `going` are capacity-checked under a row-level lock, so an event can never be oversold.

**Rules:**

* RSVPs close at `startTime`.
* A `cancelled` event rejects RSVPs.
* `"maybe"` is rejected when the event's `allowMaybe` is `false`.
* `"going"` (new or switched into) is rejected when `rsvpCounts.going` has reached `capacity`.

## Path Parameters

<ParamField path="eventId" type="string" required>
  UUID of the event.
</ParamField>

## Body Parameters

<ParamField body="status" type="string" required>
  `"going"`, `"maybe"`, or `"not_going"`.
</ParamField>

<ParamField body="userId" type="string">
  Service/master key only. RSVP on behalf of this user.
</ParamField>

## Response

Returns the [Event](/data-models/event) with refreshed `rsvpCounts` and the caller's `userRsvp`.

## Error Responses

<AccordionGroup>
  <Accordion title="Not Found / No Access — 404">
    ```json theme={null}
    { "error": "Event not found", "code": "event/not-found" }
    ```
  </Accordion>

  <Accordion title="Event Cancelled — 409">
    ```json theme={null}
    { "error": "This event has been cancelled.", "code": "event/cancelled" }
    ```
  </Accordion>

  <Accordion title="RSVPs Closed — 409">
    ```json theme={null}
    { "error": "RSVPs are closed for this event.", "code": "event/rsvp-closed" }
    ```
  </Accordion>

  <Accordion title="Maybe Disabled — 409">
    ```json theme={null}
    { "error": "This event does not allow a 'maybe' RSVP.", "code": "event/maybe-disabled" }
    ```
  </Accordion>

  <Accordion title="At Capacity — 409">
    ```json theme={null}
    { "error": "This event is at capacity.", "code": "event/full" }
    ```
  </Accordion>
</AccordionGroup>

See also: [useSetRsvp](/hooks/events/use-set-rsvp)