ExactLengthValidator<T> class

A validator that checks if the length of a value is equal to exactLength.

The ExactLengthValidator can be used with FieldControllers holding values of types String, List, Map or Set. It ensures that the length is equal to exactLength.

If the value is null it is treated as valid by default.

Properties

• exactLength: The exact allowed length for the value.
• message: An optional custom error message to display when invalid.

Example

FieldController<String> field = FieldController(
  key: 'name',
  validators:[ExactLengthValidator(3)],
);

// If field.value = 'Maria', validation fails.
// If field.value = 'João Pedro', validation fails.
// If field.value = 'Ana', validation passes.

See also

• FormyValidator, the base class for custom validators.
• ValidationResult, which describes the outcome of validation.
• FieldController, which holds the field value to be validated.