.undefined

The .undefined rule is used to ensure that the value of a given property is undefined.

note

Note that this rule considers null values to be invalid. If you need to allow for both null and undefined values (or just null values), you may use the .null rule instead.

Example

import { Validator } from 'fluentvalidation-ts';

type FormModel = {
  customerId?: number | null;
};

class FormValidator extends Validator<FormModel> {
  constructor() {
    super();

    this.ruleFor('customerId').undefined();
  }
}

const formValidator = new FormValidator();

formValidator.validate({});
// ✔ {}

formValidator.validate({ customerId: undefined });
// ✔ {}

formValidator.validate({ customerId: 100 });
// ❌ { customerId: 'Value must be undefined' }

formValidator.validate({ customerId: null });
// ❌ { customerId: 'Value must be undefined' }

Reference

.undefined()

A validation rule which ensures that the given property is undefined.

Example Message

Value must be undefined