🌿 Vine

Vine is a robust, typed validation library for Dart/Flutter, designed to simplify and secure data management in applications inspired by Vine.js..

Its main objective is to solve the recurring problem of validating user input, external APIs or internal configurations, a critical step that is often a source of errors and complexity in development.

Unlike manual methods or ad hoc checks, Vine offers a structured, declarative approach to defining validation schemes, ensuring that data complies with an expected format before it is used, which reduces bugs and improves reliability.

🛠 Key features

Feature	Description
✅ Type-Safe Validation	Define schemas with a fluent API and ensure data integrity
🧱 Rich Set of Validators	Strings, numbers, booleans, arrays, enums, objects, and more
🔄 Data Transformation	Trim, normalize, and transform values during validation
🚧 Null Safety	Full support for nullable and optional fields
⚙️ Composable	Compiled and reusable schemas
⚡ Fast Performance	~ 29 000 000 ops/s
📦 Extremely small size	Package size < 21kb
🚀 OpenApi reporter	Export your schemas as OpenApi spec

🚀 Usage

Vine is a data structure validation library for Dart. You may use it to validate the HTTP request body or any data in your backend applications.

See related article in Dev.to to discover how to use Vine in your Dart projects.

Built for validating form data and JSON payloads

Serializing an HTML form to FormData or a JSON object comes with its own set of quirks.

For example:

• Numbers and booleans are serialized as strings
• Checkboxes are not booleans
• And empty fields are represented as empty strings

Vine handles all these quirks natively, and you never have to perform manual normalization in your codebase.

Maintainability and reusability

This library meets the typical need for maintainability and security in dynamic ecosystems such as Flutter, where uncontrolled data can lead to crashes or vulnerabilities.

It offers an elegant solution via a fluid, chainable API, enabling complex validation rules (text length, numeric ranges, email formats, UUID, etc.) to be described in just a few lines.

For example, a user form can be validated with precise constraints (e.g. vine.string().email().minLength(5)) while transforming the data (trim, case conversion, normalisation), thus avoiding redundant code and repeated checks.

import 'package:vine/vine.dart';

void main() {
  final validator = vine.compile(
    vine.object({
      'username': vine.string().minLength(3).maxLength(20),
      'email': vine.string().email(),
      'age': vine.number().min(18).optional(),
      'isAdmin': vine.boolean(),
      'features': vine.array(vine.string()),
    }));

  try {
    final payload = {
      'username': 'john Doe',
      'email': 'john@example.com',
      'age': 25,
      'isAdmin': true,
      'features': ['MANAGE'],
    };

    final data = validator.validate(payload);
    print('Valid data: $data');
  } on ValidationException catch (e) {
    print('Validation error: ${e.message}');
  }
}

OpenAPI reporter

Vine can generate an OpenAPI schema from your validation schemas. This feature is useful when you want to document your API

final schema = vine.object({
  'stringField': vine.string().minLength(3).maxLength(20),
  'emailField': vine.string().email(),
  'numberField': vine.number().min(18).max(100),
  'booleanField': vine.boolean(),
  'enumField': vine.enumerate(MyEnum.values),
  'arrayField': vine.array(vine.string().minLength(3).maxLength(20)).minLength(1),
  'unionField': vine.union([
    vine.string().minLength(3).maxLength(20),
    vine.number().min(10).max(20),
  ]),
});

final reporter = vine.openApi.report(schemas: {'MySchema': schema});
print(reporter);

❤️ Credit

I would like to thank Harminder Virk for all his open-source work on Adonis.js and for his permission to reuse the name Vine for this package.