ValidationRule class

Represents a single validation rule that can be applied to a string value.

Contains:

• validate: A function performing the actual validation.
• errorMessage: The error message returned when validation fails.

The call method executes the validation function and returns errorMessage if validation fails, or null if validation succeeds.

Example usage:

final rule = ValidationRule(
  (value) => value != null && value.isNotEmpty ? null : 'Cannot be empty',
  'Cannot be empty',
);

final result = rule(''); // result is 'Cannot be empty'
final result2 = rule('valid'); // result2 is null

Constructors

ValidationRule(ValidationFunction validate, String errorMessage)

Creates a ValidationRule with the given validate function and errorMessage.

const

Properties

errorMessage → String

The error message to return if the validation fails.

final

hashCode → int

The hash code for this object.

no setter, inherited

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

validate → ValidationFunction

The validation function to run on the input value.

final

Methods

call(String? value) → String?

Executes the validation function on value.

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 ==(Object other) → bool

The equality operator.

inherited