Auto Form Validator

A highly customizable and comprehensive Flutter package for automated form validation. auto_form_validator provides a simple, unified, and declarative way to validate all kinds of form fields in your Flutter applications.

Features

  • Comprehensive Built-in Validators: required, email, phone, password, minLength, maxLength, numeric, alphabetic, match (for password confirmation).
  • Custom Error Messages: Easily provide custom error messages for each validator.
  • Custom Regex Support: Pass your own regular expressions to override default patterns or create entirely new validation rules.
  • Custom Functions: Provide any custom boolean-returning function for complex validation logic.
  • Validator Composition: Chain multiple validators together for a single form field using AutoFormValidator.compose(). First error encountered will be returned.
  • Zero Dependencies: Pure Dart utility classes, lightweight and fast.

Getting started

Add this package to your pubspec.yaml:

dependencies:
  auto_form_validator:
    path: ../ # Replace with version when published to pub.dev

Then run flutter pub get.

Usage

Import the package in your file:

import 'package:auto_form_validator/auto_form_validator.dart';

Basic Validation

Use a single validator on a TextFormField:

TextFormField(
  decoration: const InputDecoration(labelText: 'Email'),
  validator: (value) => AutoFormValidator.email(value, message: 'Invalid email address'),
)

Composing Multiple Validators & Auto-Scrolling

To check for multiple rules (e.g., required AND valid email AND custom rule), use AutoFormValidator.compose().

You can also pass an optional focusNode to compose(). If validation fails, it will automatically request focus on the first failed field in your form, seamlessly scrolling the user to it!

// First, create a FocusNode in your State class
final _ageFocus = FocusNode();

// Pass it to your TextFormField AND to the compose method
TextFormField(
  focusNode: _ageFocus,
  decoration: const InputDecoration(labelText: 'Age'),
  validator: AutoFormValidator.compose([
    (val) => AutoFormValidator.required(val, message: 'Age is required'),
    (val) => AutoFormValidator.numeric(val, message: 'Age must be a number'),
    (val) => AutoFormValidator.custom(
          val,
          (v) => int.tryParse(v ?? '') != null && int.parse(v!) >= 18,
          message: 'You must be at least 18 years old',
        ),
  ], focusNode: _ageFocus),
)

Customizing Regex

You can override the default regex for email, phone, or passwords, or create entirely custom ones using AutoFormValidator.regex():

TextFormField(
  decoration: const InputDecoration(labelText: 'Custom ID Code'),
  validator: (val) => AutoFormValidator.regex(
    val, 
    RegExp(r'^[A-Z]{3}-\d{4}$'), 
    message: 'Must follow format ABC-1234',
  ),
)

Checking for Matching Values

Perfect for "Confirm Password" scenarios:

TextFormField(
  decoration: const InputDecoration(labelText: 'Confirm Password'),
  obscureText: true,
  validator: (val) => AutoFormValidator.match(
    val, 
    _passwordController.text, 
    message: 'Passwords do not match',
  ),
)

Available Validators

Validator Description
required Field cannot be null or empty string.
email Validates standard email formats.
phone Validates standard phone number formats (+ and 7-15 digits).
password Validates strong password (8+ chars, min 1 letter, min 1 number).
minLength Enforces a minimum character length.
maxLength Enforces a maximum character length.
numeric Ensures input only contains numbers.
alphabetic Ensures input only contains alphabetic characters (a-z, A-Z).
alphaNumeric Ensures input contains only letters and numbers.
integer Validates if the input is a valid integer.
range Validates if a numeric input falls within a specific range (inclusive).
regex Validates against any user-provided RegExp.
match Validates that the input matches another provided string.
custom Validates against a user-provided boolean function.
url Validates standard URL formats.
lowercase Validates if the input is completely lowercase.
uppercase Validates if the input is completely uppercase.
contains Validates if the input contains a specific substring.
hexColor Validates if the input is a valid hex color code.
creditCard Validates a credit card number using basic format and Luhn algorithm.
ipAddress Validates if the input is a valid IPv4 or IPv6 address.
date Validates if the input is a valid Date in YYYY-MM-DD format.
macAddress Validates if the input is a valid MAC address.
uuid Validates if the input is a valid UUID/GUID.
base64 Validates if the input is a valid Base64 string.
json Validates if the input is a valid JSON string.
inList Validates if the input value exists in the provided list.
notInList Validates if the input value does NOT exist in the provided list.
startsWith Validates if the input starts with a specific substring.
endsWith Validates if the input ends with a specific substring.
hasUppercase Validates if the input contains at least one uppercase letter.
hasLowercase Validates if the input contains at least one lowercase letter.
hasNumber Validates if the input contains at least one number.
hasSpecialCharacter Validates if the input contains at least one special character.
slug Validates if the input is a valid URL slug.
boolean Validates if the input represents a boolean (true or false).

Additional information

Check out the example folder in the repository for a fully working Flutter app demonstrating this package in action.

If you find a bug or have a feature request, please file an issue on the repository!

License

  • This package is licensed under the Apache-2.0 License.

Libraries

auto_form_validator