Overview

Ack is a schema validation library for Dart and Flutter that helps you validate data with a simple, fluent API. Ack is short for "acknowledgment".

Why Use Ack?

• Simplify Validation: Easily handle complex data validation logic.
• Ensure Data Integrity: Guarantee data consistency from external sources (APIs, user input).
• Single Source of Truth: Define data structures and rules in one place.
• Reduce Boilerplate: Minimize repetitive validation code.

What Ack Does

• Validates data against defined schemas
• Provides detailed error messages for validation failures
• Generates JSON Schema specifications
• Works seamlessly with JSON data from APIs

Quick Start

Add Ack to your project:

dart pub add ack

Basic Usage

import 'package:ack/ack.dart';

// Define the structure and rules for a user object.
final userSchema = Ack.object({
  'name': Ack.string().minLength(2).maxLength(50), // Name must be a string between 2 and 50 chars.
  'age': Ack.integer().min(0).max(120),            // Age must be an integer between 0 and 120.
  'email': Ack.string().email().nullable(),        // Email must be a valid format, but can be null.
}); // All fields are required by default

// Data to validate.
final dataToValidate = {
  'name': 'John',
  'age': 30,
  'email': 'john@example.com'
};

// Perform the validation against the schema.
final result = userSchema.safeParse(dataToValidate);

// Check the validation outcome.
if (result.isOk) {
  // Validation passed, safely access the validated data.
  final validData = result.getOrThrow();
  print('Valid data: $validData');
} else {
  // Validation failed, access the detailed error.
  final error = result.getError();
  print('Validation Error: $error'); // Use error.toString() for full details.
}

Core Features

Ack provides a comprehensive set of features for data validation and transformation:

• Schema Types: Define data structures with strings, numbers, booleans, lists, objects, and more
• Validation Rules: Apply constraints like length, range, pattern matching, and custom validators
• Error Handling: Get detailed, structured error messages for validation failures
• JSON Serialization: Convert between JSON and typed models
• Schema Validation: Comprehensive schema validation with fluent API

Next Steps

Ready to dive deeper? Start with the Quickstart Tutorial for a step-by-step guide, or explore specific topics:

• Schema Types - Learn about all available schema types
• Validation Rules - Master validation constraints
• Error Handling - Handle validation errors effectively
• Flutter Integration - Validate Flutter forms

Advanced Features

Ack provides powerful features for complex validation scenarios:

• Nested validation: Validate deeply nested objects and lists
• Custom validation: Add custom logic with .refine() and constraints
• Union types: Handle polymorphic data with anyOf() and discriminated unions
• Data transformation: Transform validated data with .transform()
• JSON Schema generation: Generate JSON Schema specs for API documentation

For detailed examples and usage patterns, see the Common Recipes guide.