Raising a failure: reject

reject ends the callable with a declared failure:

action reserve(product: Product, requested: Quantity) fails QuantityUnavailable -> Reservation {    if (requested > product.available) {        reject QuantityUnavailable {            available: product.available            product_id: product.id            requested: requested        }    }    ...}

The block after the failure's name gives every client and internal field at once. A failure with no fields is rejected by its name alone. A missing, unknown or repeated field is an error.

There is no reject "text" and no throw: every failure has a declared type. reject can also be the result of a match arm (Match).

Two things can never go in a failure's fields: a secret setting (configuration.secret_flow, see Secrets), and the signed-in caller (Who is calling).