dup 1.0.0

A powerful, flexible schema-based validation library for Dart and Flutter, inspired by JavaScript's yup.

dup

A powerful, flexible validation library for Dart and Flutter, inspired by JavaScript's yup.

Features

• Schema-based validation for forms and data models
• Chainable, composable validation rules
• Customizable error messages and labels
• Exception-based error handling
• Easy integration with Flutter

Installation

Add dup to your pubspec.yaml:

dependencies:
dup: ^1.0.0

Then run:

dart pub get

Usage

dup enables you to define validation rules for your data using a schema-based approach, making your validation logic clean, reusable, and maintainable.

1. Define a validation schema

First, define a schema that describes the validation rules for each field.
Each field uses a validator instance (e.g., ValidateString, ValidateNumber).

import 'package:dup/dup.dart';

final BaseValidatorSchema schema = BaseValidatorSchema({
  'email': ValidateString()
      .email()
      .required()
      .setLabel('Email'),
  'password': ValidateString()
      .password()
      .required()
      .setLabel('Password'),
  'age': ValidateNumber()
      .min(18)
      .max(99)
      .setLabel('Age'),
});

• email must be a valid email address and is required.
• password must meet your password rule and is required.
• age must be between 18 and 99.

2. Prepare request data

Create a Map containing the values you want to validate.

final request = {
  'email': '[e-mail]',
  'password': '1234',
  'age': 20,
};

3. Validate

Call useUiForm.validate() to validate your data against the schema.
If validation fails, a FormValidationException will be thrown with a map of error messages.

try {
  await useUiForm.validate(schema, request);
  // Validation passed!
} catch (e) {
  print(e.toString); // Example: 'Invalid email format.'
}

---

Example: Validating a request object

You can encapsulate validation logic inside your data classes for better structure and reusability.

1. Define your request class

import 'package:dup/dup.dart';

class RequestObject {
  String? title;
  String? contents;

  RequestObject({this.title, this.contents});

  /// Validates the request fields using dup's schema-based validation.
  Future validate() async {
    final BaseValidatorSchema schema = BaseValidatorSchema({
      'title': ValidateString()
          .min(2)
          .setLabel('Title')
          .required(),
      'contents': ValidateString()
          .min(2)
          .setLabel('Contents')
          .required(),
    });
    await useUiForm.validate(schema, {
      'title': title,
      'contents': contents,
    });
  }
}

• title is required and must be at least 2 characters long.
• contents is required and must be at least 2 characters long.

2. Use your request class and handle validation

void main() async {
  final RequestObject params = RequestObject(title: 'Hello', contents: 'W');
  try {
    await params.validate();
    print('Validation passed!');
  } catch (e) {
    print(e.toString); // 'Contents must be at least 2 characters long.'
  }
}

---

How it works

• BaseValidator: Abstract class for creating custom validators.
• ValidateString / ValidateNumber / ValidateList: Built-in validator classes for strings, numbers, and lists.
• BaseValidatorSchema: Holds the schema definition (map of field names to validators).
• UiFormService: Provides the validate() method to check a schema and request map, and throws FormValidationException on failure.
• FormValidationException: Contains a map of field names to error messages.

Tips

• You can chain multiple validation rules for each field.
• Use .setLabel() to customize error messages with a user-friendly field name.

API Overview

• BaseValidator: Abstract base class for validators
• ValidateString: String validation (min, max, email, password, etc.)
• ValidateNumber: Number validation (min, max, isInteger, etc.)
• ValidateList: List validation
• BaseValidatorSchema: Schema for form validation
• UiFormService: Service for validating schemas and handling errors
• FormValidationException: Exception thrown on validation failure

Links

• API Reference
• GitHub Repository