PredicateValidator<T extends Object> class

Builds a validator from a plain predicate — a one-off check without declaring a new class.

final finite = PredicateValidator<num>(
  (v) => v.isFinite,
  error: 'Must be a finite number',
);
finite(1.5);        // null
finite(double.nan); // 'Must be a finite number'
finite(null);       // null — empty input is skipped by default

Like every non-text validator it treats only null as empty, so a PredicateValidator<String> does run its predicate on blank strings. Reach for the text validators (or check blankness in the predicate) when blank input should be skipped.

Inheritance
Available extensions

Constructors

PredicateValidator(bool predicate(T value), {required String error, bool ignoreEmptyValues = true})
Constructs a validator that reports error when predicate returns false.
const

Properties

error → String
The error message returned when validation fails.
finalinherited
hashCode → int
The hash code for this object.
no setterinherited
ignoreEmptyValues → bool
Whether empty input (see isEmpty) short-circuits to "valid".
finalinherited
predicate → bool Function(T value)
Decides whether a non-empty value is valid.
final
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited

Methods

call(T? value) → String?
Validates value: returns null when it is acceptable, error when it is not.
inherited
isEmpty(T value) → bool
Whether a non-null value counts as "empty" for this value type.
inherited
isValid(T value) → bool
Checks whether a non-empty value satisfies the validation criteria.
override
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
toString() → String
A string representation of this object.
inherited

Operators

operator &(Validator<T> other) → ValidatorGroup<T>

Available on Validator<T>, provided by the ValidatorComposition extension

Combines this validator with other; the result reports the first error.
operator ==(Object other) → bool
The equality operator.
inherited