Error Handling

Validation failures are represented by ValidationException and MessageBag.

Throwing on Failure

const validator = new Validator(data, rules);
await validator.validate(); // throws ValidationException on failure

Catching ValidationException

import { ValidationException } from 'kanun';

try {
  await validator.validate();
} catch (error) {
  if (error instanceof ValidationException) {
    console.log(error.message);
    console.log(error.errors());
  }
}

Working with MessageBag

const errors = validator.errors();

errors.all(); // flat array of all messages
errors.get('email'); // messages for one field
errors.first('email'); // first message for one field
errors.isEmpty(); // true/false
errors.toArray(); // structured object by field

Error Bags

Use named bags when you validate multiple forms/contexts:

await validator.validateWithBag('profile');

validator.errorBag(); // 'profile'

Fail-fast vs Collect-all

• Default behavior collects all validation errors.
• stopOnFirstFailure() exits early on first failure.

const validator = new Validator(data, rules).stopOnFirstFailure();