auto_validated_form

A reactive, granular, and boilerplate-free form validation package for Flutter.

Note

This package is still under development, so if you're looking for a more mature and reliable solution with similar functionality, take a look at reactive_forms.

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Demo

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Why auto_validated_form?

Form validation in Flutter often requires frustrating compromises:

• Keystroke validation is annoying: Validating immediately on the first keystroke (AutovalidateMode.always) complains before the user even finishes typing.
• Unfocus validation is too late: Validating only on unfocus or submit makes it difficult to reactively enable or disable a submit button as soon as the user enters valid data.
• Rebuilding the whole tree: Standard reactive forms often require listening to controllers with setState or rebuilding entire screens, causing unnecessary re-renders.

auto_validated_form solves this with a smart validation lifecycle:

1. Intelligent Triggering: Untouched fields validate when losing focus. Once touched, they validate smoothly as the user types.
2. Granular Reactivity: Submit buttons and error displays rebuild only when needed without re-rendering all your input fields.
3. Clean Architecture: Decouple validation state tracking from your presentation widgets using ValidationStateTracker and AutoValidatedFormScope.

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Features

• ⚡ Smart Validation Lifecycle: Unobtrusive on blur when empty, live on keystroke once edited.
• 🎯 Targeted Reactive Rebuilds: Use AutoValidatedFormBuilder to rebuild only the submit button or error views.
• 🔌 Drop-in TextField Replacement: AutoValidatedTextField supports all standard Flutter TextField styling and behavior.
• 🛠️ Custom Input Support: Wrap any custom widget with AutoValidatedField.
• 📊 Powerful State Helpers: Easily query areAllValid, errorMessages, hasErrors, or errorsMap.
• 🔄 Form Resetting: Reset all fields to their clean initial state in a single call.

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Getting Started

Add auto_validated_form to your pubspec.yaml:

dependencies:
  auto_validated_form: ^0.0.1

Or install it via terminal:

flutter pub add auto_validated_form

Import the package in your Dart code:

import 'package:auto_validated_form/auto_validated_form.dart';

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Quick Start

Setting up an auto-validated form takes 4 easy steps:

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

class QuickStartForm extends StatefulWidget {
  const QuickStartForm({super.key});

  @override
  State<QuickStartForm> createState() => _QuickStartFormState();
}

class _QuickStartFormState extends State<QuickStartForm> {
  // 1. Initialize the tracker with your field IDs
  late final ValidationStateTracker _tracker;
  final TextEditingController _emailController = TextEditingController();
  final TextEditingController _passwordController = TextEditingController();

  @override
  void initState() {
    super.initState();
    _tracker = ValidationStateTracker.defaultFalse(['email', 'password']);
  }

  @override
  void dispose() {
    _tracker.dispose();
    _emailController.dispose();
    _passwordController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    // 2. Wrap your form in AutoValidatedFormScope
    return Scaffold(
      body: AutoValidatedFormScope(
        validationStateTracker: _tracker,
        child: Padding(
          padding: const EdgeInsets.all(16.0),
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            mainAxisSize: MainAxisSize.max,
            children: [
              // 3. Use AutoValidatedTextField
              AutoValidatedTextField(
                controller: _emailController,
                decoration: const InputDecoration(labelText: 'Email'),
                validationListener: _tracker.validationListener('email'),
                validator: (value) {
                  if (value == null || value.isEmpty) {
                    return 'Please enter some text';
                  }
                  if (!RegExp(r'^[^@]+@[^@]+\.[^@]+').hasMatch(value)) {
                    return 'Please enter a valid email address';
                  }
                  return null;
                },
              ),
              const SizedBox(height: 16),
              AutoValidatedTextField(
                controller: _passwordController,
                obscureText: true,
                decoration: const InputDecoration(labelText: 'Password'),
                validationListener: _tracker.validationListener('password'),
                validator: (value) {
                  if (value == null || value.isEmpty) {
                    return 'Please enter some text';
                  }
                  if (value.length < 6) {
                    return 'Password must be at least 6 characters';
                  }
                  return null;
                },
              ),
              const SizedBox(height: 24),
              // 4. Reactively enable the submit button
              AutoValidatedFormBuilder(
                builder: (context, fields, isValid, child) {
                  return ElevatedButton(
                    onPressed: isValid ? _submit : null,
                    child: child!,
                  );
                },
                child: const Text('Submit'),
              ),
            ],
          ),
        ),
      ),
    );
  }

  void _submit() {
    ScaffoldMessenger.of(context).showSnackBar(
      const SnackBar(content: Text('Form Submitted!')),
    );
  }
}

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Practical Recipes

1. Auto-Validated Submit Button (Active / Inactive)

Keep your submit button disabled (inactive) until all form fields are valid, and immediately activate it as soon as validation passes—without re-rendering any of your input fields:

AutoValidatedFormBuilder(
  // Pass static children to prevent unnecessary rebuilds
  child: const Text('Submit Application'),
  builder: (context, fields, isValid, child) {
    return ElevatedButton(
      // When isValid is true, button is enabled.
      // Setting onPressed to null automatically disables (deactivates) Flutter buttons.
      onPressed: isValid ? () => _submitForm() : null,
      style: ElevatedButton.styleFrom(
        backgroundColor: isValid ? Theme.of(context).primaryColor : Colors.grey.shade400,
        foregroundColor: Colors.white,
      ),
      child: Row(
        mainAxisSize: MainAxisSize.min,
        children: [
          Icon(isValid ? Icons.check_circle_outline : Icons.lock_outline, size: 18),
          const SizedBox(width: 8),
          child!,
        ],
      ),
    );
  },
)

Tip: Both isValid and fields.areAllValid provide the form-wide validity status. In standard Flutter buttons (ElevatedButton, FilledButton, TextButton, OutlinedButton), passing null to onPressed automatically triggers the platform's disabled styling and touch rejection.

2. Centralized Error Summary List

You can display all active errors in one place (e.g., at the top or bottom of a form) using fields.errorMessages:

AutoValidatedFormBuilder(
  builder: (context, fields, isValid, child) {
    final errors = fields.errorMessages;
    if (errors.isEmpty) return const SizedBox.shrink();

    return Container(
      padding: const EdgeInsets.all(12),
      decoration: BoxDecoration(
        color: Colors.red.shade50,
        borderRadius: BorderRadius.circular(8),
      ),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          for (final msg in errors)
            Text('• $msg', style: const TextStyle(color: Colors.red)),
        ],
      ),
    );
  },
)

3. Custom Input Widgets with AutoValidatedField

If you are not using standard TextField widgets (or want complete control over how errors are rendered), use AutoValidatedField:

AutoValidatedField(
  controller: _customController,
  validator: (val) => val == null || val.isEmpty ? 'Field required' : null,
  validationListener: _tracker.validationListener('custom_field'),
  fieldBuilder: (context, errorText) {
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        CustomInputBox(controller: _customController),
        if (errorText.isNotEmpty)
          Text(errorText, style: const TextStyle(color: Colors.red)),
      ],
    );
  },
)

4. Resetting Form State

To clear your inputs and restore the tracker to its initial unvalidated state:

void _resetForm() {
  _emailController.clear();
  _passwordController.clear();
  _tracker.reset();
}

5. Custom Error Presentation on AutoValidatedTextField

You can hide inline error text or supply a custom error widget builder:

AutoValidatedTextField(
  controller: _controller,
  validationListener: _tracker.validationListener('field'),
  validator: (val) => val == null || val.isEmpty ? 'Required' : null,
  // Custom error widget
  errorWidgetBuilder: (errorText) => Text(
    '⚠️ $errorText',
    style: const TextStyle(color: Colors.deepOrange, fontSize: 12),
  ),
  // Or hide the inline error entirely:
  // hideError: true,
)

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Architecture & API Overview

Component	Role
ValidationStateTracker	Central controller holding reactive validation states (ValueNotifier<Map<String, FieldModel>>).
AutoValidatedFormScope	InheritedWidget that makes the ValidationStateTracker accessible to all descendant widgets.
AutoValidatedTextField	Drop-in TextField that wires itself to validation lifecycle listeners automatically.
AutoValidatedField	Generic wrapper accepting any custom widget via fieldBuilder(context, errorText).
AutoValidatedFormBuilder	Reactive builder that rebuilds only when form validity or field states change.
FieldModelMapExtension	Convenience getters on Map<String, FieldModel> (areAllValid, errorMessages, errorsMap, hasErrors).
AutoValidatedFormController	Imperative controller for triggering validation manually when needed.

ValidationStateTracker Constructors

• ValidationStateTracker.defaultFalse(List<String> ids): Initializes specified field IDs with unvalidated states.
• ValidationStateTracker.byList(List<FieldModel> fields): Initializes tracker with a list of custom FieldModel instances.
• ValidationStateTracker.byFields(Map<String, FieldModel> fields): Initializes tracker with an explicit map of FieldModel instances.

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Comparison: Traditional Flutter vs. auto_validated_form

Check out the example/ directory for a complete, runnable app demonstrating:

• Side-by-side comparison between Flutter's default Form/TextFormField approach and auto_validated_form.
• How auto_validated_form eliminates boilerplate listener chains and timing delays.

To run the example app:

cd example
flutter run

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Contributing

Contributions, issues, and feature requests are welcome!
Feel free to open an issue or pull request on GitHub.

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License

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