Flutter Form Builder

This package helps in creation of data collection forms in Flutter by removing the boilerplate needed to build a form, validate fields, react to changes and collect final user input.

Also included are common ready-made form input fields for FormBuilder. This gives you a convenient way of adding common ready-made input fields instead of creating your own FormBuilderField from scratch.

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Call for Maintainers

We are looking for maintainers to contribute to the development and maintenance of Flutter Form Builder Ecosystem. Is very important to keep the project alive and growing, so we need your help to keep it up to date and with new features. You can contribute in many ways, we describe some of them in Support section.

• Features
• Inputs
  • Parameters
• Use
  • Setup
  • Basic use
  • Specific uses
    • Validate and get values
    • Format date and time values
    • Building your own custom field
    • Programmatically changing field value
    • Programmatically inducing an error
    • Conditional validation
    • Implement reset, clear or other button into field
• Support
  • Contribute
  • Questions and answers
  • Donations
• Roadmap
• Ecosystem
• Thanks to

Features

• Create a form with several type of inputs
• Get values from form by easy way
• Apply validators to inputs fields
• React to form fields changes and validations

Inputs

The currently supported fields include:

• FormBuilderCheckbox - Single checkbox field
• FormBuilderCheckboxGroup - List of checkboxes for multiple selection
• FormBuilderChoiceChip - Creates a chip that acts like a radio button.
• FormBuilderDateRangePicker - For selection of a range of dates
• FormBuilderDateTimePicker - For Date, Time and DateTime input
• FormBuilderDropdown - Used to select one value from a list as a Dropdown
• FormBuilderFilterChip - Creates a chip that acts like a checkbox
• FormBuilderRadioGroup - Used to select one value from a list of Radio Widgets
• FormBuilderRangeSlider - Used to select a range from a range of values
• FormBuilderSlider - For selection of a numerical value on a slider
• FormBuilderSwitch - On/Off switch field
• FormBuilderTextField - A Material Design text field input

Parameters

In order to create an input field in the form, along with the label, and any applicable validation, there are several attributes that are supported by all types of inputs namely:

The rest of the attributes will be determined by the type of Widget being used.

Use

Setup

No specific setup required: only install the dependency and use :)

Basic use

final _formKey = GlobalKey<FormBuilderState>();

FormBuilder(
    key: _formKey,
    child:  FormBuilderTextField(
        name: 'text',
        onChanged: (val) {
            print(val); // Print the text value write into TextField
        },
    ),
)

See pub.dev example tab or github code for more details

Specific uses

Validate and get values

Note: Validators are in a separate package (form_builder_validators).

final _formKey = GlobalKey<FormBuilderState>();

FormBuilder(
  key: _formKey,
  child: Column(
    children: [
      FormBuilderTextField(
        key: _emailFieldKey,
        name: 'email',
        decoration: const InputDecoration(labelText: 'Email'),
        validator: FormBuilderValidators.compose([
          FormBuilderValidators.required(),
          FormBuilderValidators.email(),
        ]),
      ),
      const SizedBox(height: 10),
      FormBuilderTextField(
        name: 'password',
        decoration: const InputDecoration(labelText: 'Password'),
        obscureText: true,
        validator: FormBuilderValidators.compose([
          FormBuilderValidators.required(),
        ]),
      ),
      MaterialButton(
        color: Theme.of(context).colorScheme.secondary,
        onPressed: () {
          // Validate and save the form values
          _formKey.currentState?.saveAndValidate();
          debugPrint(_formKey.currentState?.value.toString());

          // On another side, can access all field values without saving form with instantValues
          _formKey.currentState?.validate();
          debugPrint(_formKey.currentState?.instantValue.toString());
        },
        child: const Text('Login'),
      )
    ],
  ),
),

For a complete example that enables or disables the submit button from form state and validates an email field conditionally, see Submit Button State.

Format date and time values

FormBuilderDateTimePicker.format expects a DateFormat from the intl package.

import 'package:intl/intl.dart';

FormBuilderDateTimePicker(
  name: 'date',
  inputType: InputType.date,
  format: DateFormat('yyyy-MM-dd'),
)

Building your own custom field

To build your own field within a FormBuilder, we use FormBuilderField which will require that you define your own field.

var options = ["Option 1", "Option 2", "Option 3"];

FormBuilderField(
  name: "name",
  validator: FormBuilderValidators.compose([
    FormBuilderValidators.required(),
  ]),
  builder: (FormFieldState<dynamic> field) {
    return InputDecorator(
      decoration: InputDecoration(
        labelText: "Select option",
        contentPadding:
            EdgeInsets.only(top: 10.0, bottom: 0.0),
        border: InputBorder.none,
        errorText: field.errorText,
      ),
      child: Container(
        height: 200,
        child: CupertinoPicker(
          itemExtent: 30,
          children: options.map((c) => Text(c)).toList(),
          onSelectedItemChanged: (index) {
            field.didChange(options[index]);
          },
        ),
      ),
    );
  },
),

Programmatically changing field value

You can either change the value of one field at a time like so:

_formKey.currentState.fields['color_picker'].didChange(Colors.black);

Or multiple fields value like so:

_formKey.currentState.patchValue({
  'age': '50',
  'slider': 6.7,
  'filter_chip': ['Test 1'],
  'choice_chip': 'Test 2',
  'rate': 4,
  'chips_test': [
    Contact(
        'Andrew',
        'stock@man.com',
        'https://d2gg9evh47fn9z.cloudfront.net/800px_COLOURBOX4057996.jpg',
    ),
  ],
});

Programmatically inducing an error

Using form state key or field state key

final _formKey = GlobalKey<FormBuilderState>();
final _emailFieldKey = GlobalKey<FormBuilderFieldState>();
...
FormBuilder(
  key: _formKey,
  child: Column(
    children: [
      FormBuilderTextField(
        key: _emailFieldKey,
        name: 'email',
        decoration: const InputDecoration(labelText: 'Email'),
        validator: FormBuilderValidators.compose([
          FormBuilderValidators.required(),
          FormBuilderValidators.email(),
        ]),
      ),
      ElevatedButton(
        child: const Text('Submit'),
        onPressed: () async {
          if(await checkIfEmailExists()){
            // Either invalidate using Form Key
            _formKey.currentState?.fields['email']?.invalidate('Email already taken');
            // OR invalidate using Field Key
            _emailFieldKey.currentState?.invalidate('Email already taken');
          }
        },
      ),
    ],
  ),
),

Validation focus and auto-scroll options

validate and saveAndValidate can focus the first invalid field and scroll it into view:

final isValid = _formKey.currentState?.saveAndValidate(
  focusOnInvalid: true,
  autoScrollWhenFocusOnInvalid: true,
);

focusOnInvalid defaults to true, and autoScrollWhenFocusOnInvalid defaults to false. This is useful when the first invalid field is not a text field or is inside a custom field that does not automatically scroll into view when focused.

The same behavior can be used when setting a custom field error:

_emailFieldKey.currentState?.invalidate(
  'Email already taken',
  shouldFocus: true,
  shouldAutoScrollWhenFocus: true,
);

Using InputDecoration.errorText

Declare a variable to hold your error:

String _emailError;

Use the variable as the errorText within InputDecoration

FormBuilderTextField(
  name: 'email',
  decoration: InputDecoration(
    labelText: 'Email',
    errorText: _emailError,
  ),
  validator: FormBuilderValidators.compose([
      FormBuilderValidators.required(),
      FormBuilderValidators.email(),
  ]),
),

Set the error text

ElevatedButton(
  child: Text('Submit'),
  onPressed: () async {
    setState(() => _emailError = null);
    if(await checkIfEmailExists()){
      setState(() => _emailError = 'Email already taken.');
    }
  },
),

Conditional validation

You can also validate a field based on the value of another field

FormBuilderRadioGroup(
  decoration: InputDecoration(labelText: 'My best language'),
  name: 'my_language',
  validator: FormBuilderValidators.required(),
  options: [
    'Dart',
    'Kotlin',
    'Java',
    'Swift',
    'Objective-C',
    'Other'
  ]
    .map((lang) => FormBuilderFieldOption(value: lang))
    .toList(growable: false),
  ),
  FormBuilderTextField(
    name: 'specify',
    decoration:
        InputDecoration(labelText: 'If Other, please specify'),
    validator: (val) {
      if (_formKey.currentState.fields['my_language']?.value ==
              'Other' &&
          (val == null || val.isEmpty)) {
        return 'Kindly specify your language';
      }
      return null;
    },
  ),

Implement reset, clear or other button into field

If you can add some button to reset specific field, can use the decoration parameter like this:

List<String> genderOptions = ['Male', 'Female', 'Other'];

FormBuilderDropdown<String>(
  name: 'gender',
  initialValue: 'Male',
  decoration: InputDecoration(
    labelText: 'Gender',
    suffix: IconButton(
      icon: const Icon(Icons.close),
      onPressed: () {
        _formKey.currentState!.fields['gender']
            ?.reset();
      },
    ),
    hintText: 'Select Gender',
  ),
  items: genderOptions
      .map((gender) => DropdownMenuItem(
            alignment: AlignmentDirectional.center,
            value: gender,
            child: Text(gender),
          ))
      .toList(),
),

Or reset value like this:

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

  @override
  State<ClearFormBuilderTextField> createState() =>
      _ClearFormBuilderTextFieldState();
}

class _ClearFormBuilderTextFieldState
    extends State<ClearFormBuilderTextField> {
  final ValueNotifier<String?> text = ValueNotifier<String?>(null);
  final textFieldKey = GlobalKey<FormBuilderFieldState>();

  @override
  Widget build(BuildContext context) {
    return FormBuilderTextField(
      autovalidateMode: AutovalidateMode.always,
      name: 'age',
      key: textFieldKey,
      onChanged: (value) {
        text.value = value;
      },
      decoration: InputDecoration(
        labelText: 'Age',
        suffixIcon: ValueListenableBuilder<String?>(
          valueListenable: text,
          child: IconButton(
            onPressed: () => textFieldKey.currentState?.didChange(null),
            tooltip: 'Clear',
            icon: const Icon(Icons.clear),
          ),
          builder: (context, value, child) =>
              (value?.isEmpty ?? true) ? const SizedBox() : child!,
        ),
      ),
    );
  }
}

Migrations

v10 to v11

Starting with version 11.0.0 this package migrated to the official material_ui library. Properties exposing Material types (e.g. InputDecoration, DropdownMenuItem, ListTileControlAffinity) now use material_ui types, so import package:material_ui/material_ui.dart instead of package:flutter/material.dart when configuring them. See the migration guide.

v9 to v10

• Remove invalidateField and invalidateFirstField methods from FormBuilderState. Use fields[name]?.invalidate(errorText) and fields.first.invalidate(errorText) instead
• [FormBuilderTextField] Deprecate canRequestFocus property. Use FocusNode.canRequestFocus. instead
• Assert on FormBuilderField.decoration.enabled property. Use FormBuilderField.enabled instead
• Easy way! Only need execute dart fix --apply on your project to fix the following changes:
  • Rename FormBuilderChoiceChip to FormBuilderChoiceChips.
  • Rename FormBuilderFilterChip to FormBuilderFilterChips.
  • [FormBuilderFilterChip] Remove maxChips property.
  • [FormBuilderDateTimePicker] Remove resetIcon property.
  • [FormBuilder] Remove onPopInvoked property.

Support

Contribute

You have some ways to contribute to this packages

• Beginner: Reporting bugs or request new features
• Intermediate: Implement new features (from issues or not) and created pull requests
• Advanced: Join to organization like a member and help coding, manage issues, dicuss new features and other things

See contribution file for more details

Questions and answers

You can question or search answers on Github discussion or on StackOverflow

Donations

Donate or become a sponsor of Flutter Form Builder Ecosystem

Roadmap

• Solve open issues, prioritizing bugs

Ecosystem

Take a look to our awesome ecosystem and all packages in there

Thanks to

All contributors