flutter_form_builder

Description:

flutter form builder

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.





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
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




Complete Form
Sign Up
Dynamic Fields
Conditional Form











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:



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.







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
},
),
)
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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'),
)
],
),
),
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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.
Read this article for step-by-step instructions on how to build your own custom field.
var options = ["Option 1", "Option 2", "Option 3"];
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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]);
},
),
),
);
},
),
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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);
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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',
'[email protected]',
'https://d2gg9evh47fn9z.cloudfront.net/800px_COLOURBOX4057996.jpg',
),
],
});
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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');
}
},
),
],
),
),
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When use invalidate and validate methods, can use two optional parameters configure the behavior
when invalidate field or form, like focus or auto scroll. Take a look on method documentation for more details
Using InputDecoration.errorText
Declare a variable to hold your error:
String _emailError;
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Use the variable as the errorText within InputDecoration
FormBuilderTextField(
name: 'email',
decoration: InputDecoration(
labelText: 'Email',
errorText: _emailError,
),
validator: FormBuilderValidators.compose([
FormBuilderValidators.required(),
FormBuilderValidators.email(),
]),
),
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Set the error text
ElevatedButton(
child: Text('Submit'),
onPressed: () async {
setState(() => _emailError = null);
if(await checkIfEmailExists()){
setState(() => _emailError = 'Email already taken.');
}
},
),
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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;
},
),
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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(),
),
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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!,
),
),
);
}
}
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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