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.
To use this plugin, add flutter_form_builder as a
dependency in your pubspec.yaml file.
- Flutter 1.20 =>
v4.* - Flutter 2.* with no
null-safety=>v5.* - Flutter 2.*
null-safety=>v6.*- some dependencies (and therefore fields)* were removed to achieve null safety
Check out the video tutorial from SyntacOps on Youtube
final _formKey = GlobalKey<FormBuilderState>();
@override
Widget build(BuildContext context) {
return Column(
children: <Widget>[
FormBuilder(
key: _formKey,
autovalidate: true,
child: Column(
children: <Widget>[
FormBuilderFilterChip(
name: 'filter_chip',
decoration: InputDecoration(
labelText: 'Select many options',
),
options: [
FormBuilderFieldOption(
value: 'Test', child: Text('Test')),
FormBuilderFieldOption(
value: 'Test 1', child: Text('Test 1')),
FormBuilderFieldOption(
value: 'Test 2', child: Text('Test 2')),
FormBuilderFieldOption(
value: 'Test 3', child: Text('Test 3')),
FormBuilderFieldOption(
value: 'Test 4', child: Text('Test 4')),
],
),
FormBuilderChoiceChip(
name: 'choice_chip',
decoration: InputDecoration(
labelText: 'Select an option',
),
options: [
FormBuilderFieldOption(
value: 'Test', child: Text('Test')),
FormBuilderFieldOption(
value: 'Test 1', child: Text('Test 1')),
FormBuilderFieldOption(
value: 'Test 2', child: Text('Test 2')),
FormBuilderFieldOption(
value: 'Test 3', child: Text('Test 3')),
FormBuilderFieldOption(
value: 'Test 4', child: Text('Test 4')),
],
),
FormBuilderDateTimePicker(
name: 'date',
// onChanged: _onChanged,
inputType: InputType.time,
decoration: InputDecoration(
labelText: 'Appointment Time',
),
initialTime: TimeOfDay(hour: 8, minute: 0),
// initialValue: DateTime.now(),
// enabled: true,
),
FormBuilderDateRangePicker(
name: 'date_range',
firstDate: DateTime(1970),
lastDate: DateTime(2030),
format: DateFormat('yyyy-MM-dd'),
onChanged: _onChanged,
decoration: InputDecoration(
labelText: 'Date Range',
helperText: 'Helper text',
hintText: 'Hint text',
),
),
FormBuilderSlider(
name: 'slider',
validator: FormBuilderValidators.compose([
FormBuilderValidators.min(context, 6),
]),
onChanged: _onChanged,
min: 0.0,
max: 10.0,
initialValue: 7.0,
divisions: 20,
activeColor: Colors.red,
inactiveColor: Colors.pink[100],
decoration: InputDecoration(
labelText: 'Number of things',
),
),
FormBuilderCheckbox(
name: 'accept_terms',
initialValue: false,
onChanged: _onChanged,
title: RichText(
text: TextSpan(
children: [
TextSpan(
text: 'I have read and agree to the ',
style: TextStyle(color: Colors.black),
),
TextSpan(
text: 'Terms and Conditions',
style: TextStyle(color: Colors.blue),
),
],
),
),
validator: FormBuilderValidators.equal(
context,
true,
errorText:
'You must accept terms and conditions to continue',
),
),
FormBuilderTextField(
name: 'age',
decoration: InputDecoration(
labelText:
'This value is passed along to the [Text.maxLines] attribute of the [Text] widget used to display the hint text.',
),
onChanged: _onChanged,
// valueTransformer: (text) => num.tryParse(text),
validator: FormBuilderValidators.compose([
FormBuilderValidators.required(context),
FormBuilderValidators.numeric(context),
FormBuilderValidators.max(context, 70),
]),
keyboardType: TextInputType.number,
),
FormBuilderDropdown(
name: 'gender',
decoration: InputDecoration(
labelText: 'Gender',
),
// initialValue: 'Male',
allowClear: true,
hint: Text('Select Gender'),
validator: FormBuilderValidators.compose(
[FormBuilderValidators.required(context)]),
items: genderOptions
.map((gender) => DropdownMenuItem(
value: gender,
child: Text('$gender'),
))
.toList(),
),
],
),
),
Row(
children: <Widget>[
Expanded(
child: MaterialButton(
color: Theme.of(context).accentColor,
child: Text(
"Submit",
style: TextStyle(color: Colors.white),
),
onPressed: () {
_formKey.currentState.save();
if (_formKey.currentState.validate()) {
print(_formKey.currentState.value);
} else {
print("validation failed");
}
},
),
),
SizedBox(width: 20),
Expanded(
child: MaterialButton(
color: Theme.of(context).accentColor,
child: Text(
"Reset",
style: TextStyle(color: Colors.white),
),
onPressed: () {
_formKey.currentState.reset();
},
),
),
],
)
],
);
}Just add the FormBuilderLocalizations.delegate in the list of your app's localizationsDelegates
return MaterialApp(
supportedLocales: [
Locale('en'),
Locale('it'),
Locale('fr'),
Locale('es'),
],
localizationsDelegates: [
FormBuilderLocalizations.delegate,
GlobalMaterialLocalizations.delegate,
GlobalWidgetsLocalizations.delegate,
],The currently supported fields include:
FormBuilderCheckbox- Single Checkbox fieldFormBuilderCheckboxGroup- List of Checkboxes for multiple selectionFormBuilderChoiceChip- Creates a chip that acts like a radio button.FormBuilderDateRangePicker- For selection of a range of datesFormBuilderDateTimePicker- ForDate,TimeandDateTimeinputFormBuilderDropdown- Used to select one value from a list as a DropdownFormBuilderFilterChip- Creates a chip that acts like a checkbox.FormBuilderRadioGroup- Used to select one value from a list of Radio WidgetsFormBuilderRangeSlider- Used to select a range from a range of valuesFormBuilderSegmentedControl- For selection of a value from theCupertinoSegmentedControlas an inputFormBuilderSlider- For selection of a numerical value on a sliderFormBuilderSwitch- On/Off switch fieldFormBuilderTextField- A Material Design text field input.
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:
| Attribute | Type | Default | Required | Description |
|---|---|---|---|---|
name |
String |
Yes |
This will form the key in the form value Map | |
initialValue |
T |
null |
No |
The initial value of the input field |
enabled |
bool |
true |
No |
Determines whether the field widget will accept user input. |
decoration |
InputDecoration |
InputDecoration() |
No |
Defines the border, labels, icons, and styles used to decorate the field. |
validator |
FormFieldValidator<T> |
null |
No |
A FormFieldValidator that will check the validity of value in the FormField |
onChanged |
ValueChanged<T> |
null |
No |
This event function will fire immediately the the field value changes |
valueTransformer |
ValueTransformer<T> |
null |
No |
Function that transforms field value before saving to form value. e.g. transform TextField value for numeric field from String to num |
| The rest of the attributes will be determined by the type of Widget being used. |
To make this package compartible with as many platforms as Flutter supports, we separated some input fields into their own packages because they depend on platform-specific plugins. Here's are the links to some of the packages that could be used with FormBuilder
- FormBuilderFilePicker - Picks image(s) from user device storage.
- FormBuilderImagePicker - Picks image(s) from Gallery or Camera.
- FormBuilderLocationField - Geographic location input.
- FormBuilderPhoneField - International phone number input.
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(context),
]),
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]);
},
),
),
);
},
),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'),
],
});The validator attribute in fields take in a FormFieldValidator which checks the validity of the
field. A FormFieldValidator returns null if validation is successful and a String for the
errorText if validation fails.
This package comes with several most common FormFieldValidators such as required, numeric, mail,
URL, min, max, minLength, maxLength, IP, credit card etc. with default errorText.
Available built-in validators include:
FormBuilderValidators.creditCard()- requires the field's value to be a valid credit card number.FormBuilderValidators.date()- requires the field's value to be a valid date string.FormBuilderValidators.email()- requires the field's value to be a valid email address.FormBuilderValidators.equal()- requires the field's value be equal to provided object.FormBuilderValidators.integer()- requires the field's value to be an integer.FormBuilderValidators.ip()- requires the field's value to be a valid IP address.FormBuilderValidators.match()- requires the field's value to match the provided regex pattern.FormBuilderValidators.max()- requires the field's value to be less than or equal to the provided number.FormBuilderValidators.maxLength()- requires the length of the field's value to be less than or equal to the provided maximum length.FormBuilderValidators.min()- requires the field's value to be greater than or equal to the provided number.FormBuilderValidators.minLength()- requires the length of the field's value to be greater than or equal to the provided minimum length.FormBuilderValidators.numeric()- requires the field's value to be a valid number.FormBuilderValidators.required()- requires the field have a non-empty value.FormBuilderValidators.url()- requires the field's value to be a valid url.
FormBuilderValidators class comes with a very useful static function named compose() which takes
any number of FormFieldValidator functions. On validation each validator is run and if any returns
a non-null value (i.e. a String), validation fails and the errorText for the field is set as the
returned string.
Validation example:
FormBuilderTextField(
name: 'age',
decoration: InputDecoration(labelText: 'Age'),
validator: FormBuilderValidators.compose([
FormBuilderValidators.numeric(context, errorText: 'La edad debe ser numérica.'),
FormBuilderValidators.max(context, 70),
(val){
if(val < 0)
return 'We cannot have a negative age';
return null;
}
]),
),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(context),
FormBuilderValidators.email(context),
]),
),Set the error text
RaisedButton(
child: Text('Submit'),
onPressed: () async {
setState(() => _emailError = null);
if(checkIfEmailExists()){
setState(() => _emailError = 'Email already taken.');
}
},
),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(context),
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;
},
),Any kind of support in the form of reporting bugs, answering questions or PRs is always appreciated.
We especially welcome efforts to internationalize/localize the package by translating the default
validation errorText strings.
-
With the app’s root directory as the current directory, generate
l10n/intl_messages.arbfromlib/localization/form_builder_localizations.dart:flutter pub pub run intl_translation:extract_to_arb --output-dir=lib/l10n lib/localization/form_builder_localizations.dart -
The
intl_messages.arbfile is a JSON format map with one entry for eachIntl.message()function defined inlib/localization/form_builder_localizations.dart. This file serves as a template for the different translations (for exampleintl_en.arbandintl_es.arbare English and Spanish translations respectively). You are therefore you are required to copy theintl_messages.arband put the content in a new file with the name of your locale with a name with formatintl_<locale>.arb(e.g.intl_fr.arbfor French Translations). -
Translate the messages in the new file to the required language.
-
With the app’s root directory as the current directory, generate
intl_messages_<locale>.dartfor yourintl_<locale>.arbfile and updateintl_messages_all.dart, which imports all of the messages files:
flutter pub run intl_translation:generate_from_arb --output-dir=lib/l10n --no-use-deferred-loading lib/localization/form_builder_localizations.dart lib/l10n/intl_<en>.arb lib/l10n/intl_messages.arb
e.g. To generate for French run: flutter pub run intl_translation:generate_from_arb --output-dir=lib/l10n --no-use-deferred-loading lib/localization/form_builder_localizations.dart lib/l10n/intl_fr.arb lib/l10n/intl_messages.arb
- Alternatively you could run the following command to generate Dart translation files for all the
intl_<locale>.arbfiles in thel10n/directory:
flutter pub pub run intl_translation:generate_from_arb --output-dir=lib/l10n --no-use-deferred-loading lib/localization/form_builder_localizations.dart lib/l10n/intl_*.arb
- Include your new language to
FormBuilderLocalization's supported languages. Go tolib/localization/form_builder_localizations.dartand include the language like so:
@override
bool isSupported(Locale locale) {
return ['en', 'es', 'fr'].contains(locale.languageCode);
}
- Submit your PR and be of help to millions of people all over the world!
If this package was helpful to you in delivering your project or you just wanna to support this package, a cup of coffee would be highly appreciated ;-)
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