payload-missing

• Route: write-events
• Description: payload is missing: expected an object with the values of the precondition
• Details: precondition, the place of the precondition in its list, counting from 0.

Why It Happens#

A precondition carries the values it checks in its payload: the subject for isSubjectPristine and isSubjectPopulated, the subject and the eventId for isSubjectOnEventId, and the query for isEventQlQueryTrue. A precondition of a known type without a payload, such as { "type": "isSubjectPristine" }, has nothing to check.

A payload that is there but lacks a value is reported by that value, for example as subject-missing or query-missing. A payload that is null is rejected with 400 Bad Request, since the body then does not have the shape the route expects.

How to Fix It#

Add the payload, with the values that the type of the precondition takes. Sending the same request again fails the same way, since the error depends on the request alone.

Example#

For a write whose only precondition is an isSubjectPristine without a payload, EventSourcingDB answers with this error, as a line of the stream, and then ends the stream with its end item:

{
  "type": "error",
  "data": {
    "code": "https://docs.eventsourcingdb.io/errors/payload-missing",
    "description": "payload is missing: expected an object with the values of the precondition",
    "details": {
      "precondition": 0
    }
  }
}