Rule<T, E> class abstract

A single validation rule.

Rules are the building blocks of validation in Formix. They validate a value of type T and return either success or an error of type E.

Creating Rules

Use PredicateRule for simple predicate-based validation:

final notEmpty = PredicateRule<String, String>(
  predicate: (value) => value.isNotEmpty,
  error: 'Cannot be empty',
);

Or extend Rule for more complex logic:

class EmailRule extends Rule<String, String> {
  @override
  ValidationResult<String, String> validate(String value) {
    final regex = RegExp(r'^[\w-\.]+@([\w-]+\.)+[\w-]{2,4}$');
    return regex.hasMatch(value)
        ? Valid(value)
        : const Invalid('Invalid email format');
  }
}

Inheritance

Object
Formix<T, E>
Rule

Available extensions

FormixExtensions

Constructors

Rule(): Creates a Rule instance.
const

Properties

hashCode → int: The hash code for this object.
no setterinherited
runtimeType → Type: A representation of the runtime type of the object.
no setterinherited

Methods

andThen(Formix<T, E> next) → Formix<T, E>: Available on Formix<T, E>, provided by the FormixExtensions extension
Chains this validator with next, running next only if this passes.
cached() → CachedFormix<T, E>: Available on Formix<T, E>, provided by the FormixExtensions extension
Wraps this validator with single-value caching.
lazy() → LazyFormix<T, E>: Available on Formix<T, E>, provided by the FormixExtensions extension
Creates a lazy validator that defers instantiation until first use.
lruCached({int maxSize = 10}) → LruCachedFormix<T, E>: Available on Formix<T, E>, provided by the FormixExtensions extension
Wraps this validator with LRU (Least Recently Used) caching.
mapError<E2>(E2 mapper(E error)) → Formix<T, E2>: Available on Formix<T, E>, provided by the FormixExtensions extension
Maps errors from type E to type E2.
noSuchMethod(Invocation invocation) → dynamic: Invoked when a nonexistent method or property is accessed.
inherited
optional({bool isEmpty(T value)?}) → Formix<T, E>: Available on Formix<T, E>, provided by the FormixExtensions extension
Makes this validator optional - skips validation when empty.
recover(T onError(List<E> errors)) → Formix<T, E>: Available on Formix<T, E>, provided by the FormixExtensions extension
Recovers from validation errors with a default value.
tap({void onValid(T value)?, void onInvalid(List<E> errors)?}) → Formix<T, E>: Available on Formix<T, E>, provided by the FormixExtensions extension
Applies side effects without affecting validation.
toString() → String: A string representation of this object.
inherited
validate(T value) → ValidationResult<T, E>: Validates value and returns a ValidationResult.
inherited
when(bool condition(T value)) → Formix<T, E>: Available on Formix<T, E>, provided by the FormixExtensions extension
Conditionally applies this validator based on condition.
whenNot(bool condition(T value)) → Formix<T, E>: Available on Formix<T, E>, provided by the FormixExtensions extension
Conditionally skips this validator based on condition.
withMessageFormatter(ErrorMessageFormatter<E> formatter) → Formix<T, String>: Available on Formix<T, E>, provided by the FormixExtensions extension
Maps errors to user-facing messages using formatter.

Operators

operator ==(Object other) → bool: The equality operator.
inherited