dox_validation

Typed input for Dart: DTO classes with generated checks, and fluent schemas like Zod.

Part of Dox, a web backend framework for Dart, like Laravel. Source code: github.com/dartondox/dox.

Install

In a Dox app you do not add it. dox_core exports it. Outside Dox:

dart pub add dox_validation
dart pub add dev:dox_builder dev:build_runner

Dox 3.x is in alpha (3.0.0-alpha.x). The API can still change before the stable release.

Use it

A DTO: a class with @Dto() and rule annotations. dox_builder writes the checks.

import 'package:dox_validation/dox_validation.dart';

part 'create_user.dto.g.dart';

@Dto()
class CreateUser {
  @Length(min: 3, max: 50)
  @Trim()
  final String name;

  @Email()
  final String email;

  const CreateUser({required this.name, required this.email});

  static const DtoSchema<CreateUser> schema = $CreateUserDto;
}

Run dart run build_runner build. Then:

ParseResult<CreateUser> result = await CreateUser.schema.safeValidateMap(input);
if (!result.success) {
  print(result.errors); // {'email': 'The email is not a valid email'}
}

A fluent schema, for input you only know at runtime:

final ObjectSchema createUser = v.object(<String, Schema<Object?>>{
  'name': v.string().trim().min(3).max(50),
  'email': v.string().email(),
  'age': v.coerce.int().min(18).optional(),
});

Map<String, dynamic> data = createUser.parse(input); // throws ValidationException

Features

All problems come back at once, each with a path, a code and a message.
Messages can change per rule, per call or for the whole app (for other languages).
v.coerce turns query and form text into numbers, booleans and dates.
Async checks with refineAsync and parseAsync.
JSON Schema (draft 2020-12) with toJsonSchema(). OpenAPI uses it.
Every schema implements the Standard Schema interface.
No dependencies.

Documentation

License

MIT. See LICENSE.