How to identify if the event is a repeat event?

Question

I want to identify repeat events and mark it as not paid event programmatically and
only if the user has paid for the main event, I want to allow them for repeat events
Right now I don't see any value in event array which indicates that the event is a repeat event How can I implement it?

 "id": "49",
            "title": "Title",
            "event_title": "Title",
            "summary": "Summary",
            "description": "Description",
            "event_description": "Description",
            "event_type_id": "2",
            "participant_listing_id": "1",
            "is_public": "0",
            "start_date": "2019-01-15 20:20:00",
            "event_start_date": "2019-01-15 20:20:00",
            "end_date": "2019-01-17 00:00:00",
            "event_end_date": "2019-01-17 00:00:00",
            "is_online_registration": "0",
            "max_participants": "22",
            "event_full_text": "This event is currently full.",
            "is_monetary": "0",
            "is_map": "0",
            "is_active": "0",
            "is_show_location": "1",
            "default_role_id": "2",
            "is_email_confirm": "0",
            "is_pay_later": "0",
            "is_partial_payment": "0",
            "is_multiple_registrations": "0",
            "max_additional_participants": "0",
            "allow_same_participant_emails": "0",
            "has_waitlist": "0",
            "allow_selfcancelxfer": "0",
            "selfcancelxfer_time": "0",
            "is_template": "0",
            "created_id": "2",
            "created_date": "2019-01-07 20:22:38",
            "is_share": "0",
            "is_confirm_enabled": "1",
            "is_billing_required": "0"
        }

Answer 1

The repeat entity is stored in civicrm_recurring_entity table so you might need to use the RecurringEntity api for this purpose. The following should result the repeating events for you -

$result = civicrm_api3('RecurringEntity', 'get', [
  'sequential' => 1,
  'entity_table' => "civicrm_event",
  'parent_id' => main_event_id,
]);

Similarly the api can also be used to find repeated activities.