Nine Nines: cowboy_constraints:nonempty(3)

Name

cowboy_constraints:nonempty - Non-empty constraint

Constraint functions implement a number of different operations.

nonempty(forward | reverse, <<>>) -> {error, empty}

Reject empty values.

nonempty(forward | reverse, Bin) -> {ok, Bin}

Bin :: binary()

Accept any other binary values.

nonempty(format_error, Error) -> HumanReadable

Error         :: {empty, Bin}
HumanReadable :: iolist()

Generate a human-readable error message.

Arguments vary depending on the operation. Constraint functions always take the operation type as first argument, and the value as second argument.

The return value varies depending on the operation.

This function is not meant to be called directly.