required method

Field<bool> required({
  1. String message = '',
  2. bool exposed = false,
})

Validates that the value is not null (either true or false).

Use when the user must explicitly make a boolean choice but either true or false is acceptable.

message is the error string shown when validation fails. exposed — when true, the rule appears in Field.exposedRules.

Returns this to allow method chaining.

Example:

final newsletter = Field<bool>('newsletter')
  .required(message: 'Selecione uma opção');

newsletter.validate(); // null → error
newsletter.value = false;
newsletter.validate(); // false is valid → no error

Implementation

Field<bool> required({String message = '', bool exposed = false}) {
  return addValidator(message, (val) => val == null, exposedMessage: exposed);
}