Rules And Fluent API

Arc validation for frontend core provides a fluent API that mirrors common FluentValidation patterns.

Programmatic Rule Definition

Use ruleFor() with a chainable API:

class CreateUserCommandValidator extends CommandValidator<ICreateUserCommand> {
    constructor() {
        super();
        this.ruleFor(c => c.email).notEmpty().emailAddress();
        this.ruleFor(c => c.age).greaterThanOrEqual(18);
        this.ruleFor(c => c.name).minLength(2).maxLength(50);
    }
}

Built-in Rules

notEmpty(), notNull()
minLength(), maxLength(), length()
emailAddress()
matches(regex)
greaterThan(), greaterThanOrEqual(), lessThan(), lessThanOrEqual()

Custom Messages

Use withMessage() to override defaults:

this.ruleFor(c => c.email)
    .notEmpty()
    .withMessage('Email address is required');

Supported FluentValidation Mappings

FluentValidation	TypeScript
`NotEmpty()`	`notEmpty()`
`NotNull()`	`notNull()`
`EmailAddress()`	`emailAddress()`
`MinimumLength(n)`	`minLength(n)`
`MaximumLength(n)`	`maxLength(n)`
`Length(min, max)`	`length(min, max)`
`Matches(regex)`	`matches(regex)`
`GreaterThan(n)`	`greaterThan(n)`
`GreaterThanOrEqualTo(n)`	`greaterThanOrEqual(n)`
`LessThan(n)`	`lessThan(n)`
`LessThanOrEqualTo(n)`	`lessThanOrEqual(n)`

Note

Complex custom predicates such as .Must() are not supported for generated client-side execution.