Moform

Reactive, model-driven, and type-safe forms for Flutter without the overhead of managing a TextEditingController.

Motivation

Similar to Switch and Checkbox, changing the value of a text field should automatically update the UI. However, this requires a TextEditingController and a TextFormField to manage the state of the field.

Moform aims to be a very slim abstraction layer on top of TextFormField with 3 distinct features:

• ✅ Reactive: Automatically update the UI when value changes.
• ✅ Type-safe: Different fields for different types (String, int, double, DateTime).
• ✅ Slim: Widgets look and behave like TextFormField with minimal overhead.

Getting Started

➤ Installation

Add the following to your pubspec.yaml:

dependencies:
  flutter_localizations:
    sdk: flutter
  moform: <version>

➤ Usage

In this example, we are using a StringField to manage the value of an email field.

Using a StatefulWidget:

class EmailField extends StatefulWidget {
  @override
  State<EmailField> createState() => _EmailFieldState();
}

class _EmailFieldState extends State<EmailField> {
  String _email = '';

  @override
  Widget build(BuildContext context) {
    return StringField(
      value: _email,
      onChanged: (value) {
        setState(() => _email = value);
      },
    );
  }
}

Using Riverpod:

final emailProvider = StateProvider<String>((ref) => '');

class EmailField extends ConsumerWidget {
  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final email = ref.watch(emailProvider);

    return StringField(
      value: email,
      onChanged: (value) {
        ref.read(emailProvider.notifier).state = value;
      },
    );
  }
}

Features

➤ Typed Fields

String

StringField(
  value: email,
  onChanged: (value) {
    setState(() => email = value);
  },
);

Int

IntField(
  value: age,
  onChanged: (value) {
    setState(() => age = value);
  },
);

Double

DoubleField(
  value: weight,
  onChanged: (value) {
    setState(() => weight = value);
  },
);

DateTime

DateTimeField(
  value: date,
  onChanged: (value) {
    setState(() => date = value);
  },
);

DateTime (Date only)

DateField(
  value: date,
  onChanged: (value) {
    setState(() => date = value);
  },
);

TimeOfDay

TimeField(
  value: time,
  onChanged: (value) {
    setState(() => time = value);
  },
);

➤ Nullable Fields

There are nullable versions of the fields above:

OptionalStringField, OptionalIntField, OptionalDoubleField.

These fields have onChanged callbacks that receive String?, int?, and double? respectively.

OptionalStringField(
  value: email,
  onChanged: (String? value) { // <-- null, when the field is empty
    setState(() => email = value);
  },
);

To clear a DateTimeField, DateField, or TimeField, add the onCleared callback:

DateTimeField(
  value: date,
  onChanged: (value) {
    setState(() => date = value);
  },
  onCleared: () {
    setState(() => date = null);
  },
);

➤ Custom Styles

Provide a custom widget with the builder parameter.

Be aware that parameters like label are ignored when using a custom widget.

StringField(
  value: email,
  onChanged: (value) {
    setState(() {
      email = value;
    });
  },
  builder: (context, controller) {
    return TextField(
      controller: controller,
      decoration: const InputDecoration(
        labelText: 'Custom Field',
      ),
    );
  },
);

➤ Custom NumberFormat

Available in IntField, DoubleField, and their nullable versions.

IntField(
  value: age,
  numberFormat: NumberFormat.decimalPattern(),
  onChanged: (value) {
    setState(() => age = value);
  },
);

For more complex scenarios, you can provide a customNumberFormat. Be aware, that the parser should be the exact inverse of the formatter.

IntField(
  value: age,
  customNumberFormat: CustomNumberFormat(
    formatter: (i) => i.toString(),
    parser: (s) => int.tryParse(s),
  ),
  onChanged: (value) {
    setState(() => age = value);
  },
);

➤ Clear Button

There is a convenience onCleared callback to clear the field. If this callback is provided, a clear button will be displayed. This parameter is ignored when decoration or builder is provided.

StringField(
  value: email,
  onChanged: (value) {
    setState(() => email = value);
  },
  onCleared: () {
    setState(() => email = '');
  },
);

License

MIT License

Copyright (c) 2024 Tien Do Nam

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.