FdcFieldValidator typedef

FdcFieldValidator = String? Function(FdcRowContext row, Object? value)

Validates one field value in the context of its row.

The dataset calls the validator during validation flows. Return null when the value is valid, or a user-facing validation message when it is invalid. The callback should inspect FdcRowContext without mutating dataset state.

Implementation

typedef FdcFieldValidator = String? Function(FdcRowContext row, Object? value);