Flutter Vali

Flutter Vali is a Dart package for Flutter that provides a set of validation rules to validate form fields easily.

Installation

Add flutter_vali to your pubspec.yaml file:

dependencies:
  flutter_vali: latest_version

Then run flutter pub get to install the package.

Usage

Basic Usage

To use Flutter Vali, you need to create a Validator instance and add validation rules to it. Then, you can use the build method to get a validation function that can be used with Flutter form fields.

Example

import 'package:flutter/material.dart';
import 'package:flutter_vali/flutter_vali.dart';

class ExampleFormWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Example Form'),
      ),
      body: Form(
        child: Column(
          children: [
            TextFormField(
              decoration: InputDecoration(
                labelText: 'Enter your name',
              ),
              validator: context.validators([
                notEmptyRule(),
                minLengthRule(3, errorMessage: 'Name must be at least 3 characters long'),
                maxLengthRule(32),
              ]),
            ),
          ],
        ),
      ),
    );
  }
}

Example with fluent validation style

import 'package:flutter/material.dart';
import 'package:flutter_vali/flutter_vali.dart';

class ExampleFormWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Example Form'),
      ),
      body: Form(
        child: Column(
          children: [
            TextFormField(
              decoration: InputDecoration(
                labelText: 'Enter your name',
              ),
              validator: context.validator
                .notEmpty()
                .minLength(3, errorMessage: 'Name must be at least 3 characters long')
                .maxLength(32)
                .build()
            ),
          ],
        ),
      ),
    );
  }
}

Available Validation Rules

Rule	Description
notEmpty({String? errorMessage})	Validates that the input is not empty.
length({int length, String? errorMessage})	Validates that the input length is exactly the specified value.
minLength({int min, String? errorMessage})	Validates that the input length is at least the given minimum.
maxLength({int max, String? errorMessage})	Validates that the input length is at most the given maximum.
greaterThan({num value, String? errorMessage})	Validates that the input is greater than the specified value.
greaterThanOrEqual({num value, String? errorMessage})	Validates that the input is greater than or equal to the specified value.
lessThan({num value, String? errorMessage})	Validates that the input is less than the specified value.
lessThanOrEqual({num value, String? errorMessage})	Validates that the input is less than or equal to the specified value.
equalTo({dynamic value, String? errorMessage})	Validates that the input is equal to the specified value.
between({num min, num max, String? errorMessage})	Validates that the input is between the two specified values (inclusive).
contains({String substring, String? errorMessage})	Validates that the input contains the specified substring.
match({RegExp pattern, String? errorMessage})	Validates that the input matches the given regular expression pattern.
startsWith({String prefix, String? errorMessage})	Validates that the input starts with the specified substring.
endsWith({String suffix, String? errorMessage})	Validates that the input ends with the specified substring.
digitsOnly({String? errorMessage})	Validates that the input consists of digits only.
email({String? errorMessage})	Validates that the input is a valid email address.
phoneNumber({String? errorMessage})	Validates that the input is a valid phone number.
creditCard({String? errorMessage})	Validates that the input is a valid credit card number.
inList({List allowed, String? errorMessage})	Validates that the input is included in the specified list.
notInList({List disallowed, String? errorMessage})	Validates that the input is not included in the specified list.
date({String? errorMessage})	Validates that the input is a valid date.

Custom Validation Rules

You can create custom validation rules by extending the ValidatorRule class.

import 'package:flutter/widgets.dart';
import 'package:flutter_vali/flutter_vali';

class CustomRule extends ValidatorRule {
  const CustomRule({super.errorMessage});

  @override
  String? isValid(BuildContext context, String? value) {
    // Custom validation logic
    return value == 'custom'
        ? null
        : errorMessage ??
            defaultMessage[Localizations.localeOf(context).languageCode] ??
            defaultMessage['en'];
  }

  @override
  Map<String, String> get defaultMessage => {
    'en': 'Invalid custom value',
  };
}

extension CustomExtensions on Validator {
  Validator custom({String? errorMessage}) {
    addRule(CustomRule(errorMessage: errorMessage));
    return this;
  }
}

Supported Localization Languages

Flutter Vali supports localization for default error messages in the following languages:

• English (en)
• Arabic (ar)
• Central Kurdish Sorani (ckb)
• Afrikaans (af)
• Albanian (sq)
• Belarusian (be)
• Bulgarian (bg)
• Catalan (ca)
• Chinese Simplified (zh)
• Croatian (hr)
• Czech (cs)
• Danish (da)
• Dutch (nl)
• Estonian (et)
• Finnish (fi)
• French (fr)
• German (de)
• Greek (el)
• Hindi (hi)
• Hungarian (hu)
• Icelandic (is)
• Indonesian (id)
• Italian (it)
• Japanese (ja)
• Korean (ko)
• Latvian (lv)
• Lithuanian (lt)
• Macedonian (mk)
• Malay (ms)
• Norwegian (no)
• Polish (pl)
• Portuguese (pt)
• Romanian (ro)
• Russian (ru)
• Serbian (sr)
• Slovak (sk)
• Slovenian (sl)
• Spanish (es)
• Swedish (sv)
• Thai (th)
• Turkish (tr)
• Ukrainian (uk)
• Vietnamese (vi)

License

This project is licensed under the MIT License - see the LICENSE file for details.