flutter_form_builder 4.0.0-alpha.8

Package to build Material Form with fields like TextField, DropDown, Switches etc. with ability to create custom FormFields and composability and reuse validation functions.

Flutter FormBuilder - flutter_form_builder

This package helps in creation of Flutter Forms by providing the syntactic sugar for creating a Form Widget and reduce the boilerplate needed to build a form, validate fields, react to changes, and collect the value of the Form.

Simple Usage

To use this plugin, add flutter_form_builder as a dependency in your pubspec.yaml file.

Example

final GlobalKey<FormBuilderState> _fbKey = GlobalKey<FormBuilderState>();

Note: Avoid defining the GlobalKey inside your build method because this will create a new GlobalKey on every build cycle bringing about some erratic behavior.

Column(
  children: <Widget>[
    FormBuilder(
      key: _fbKey,
      autovalidate: true,
      // readonly: true,
      child: Column(
        children: <Widget>[
          FormBuilderFilterChip(
            attribute: '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(
            attribute: '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')),
            ],
          ),
          FormBuilderColorPickerField(
            attribute: 'color_picker',
            // initialValue: Colors.yellow,
            colorPickerType: ColorPickerType.MaterialPicker,
            decoration: InputDecoration(labelText: 'Pick Color'),
          ),
          FormBuilderChipsInput(
            decoration: InputDecoration(labelText: 'Chips'),
            attribute: 'chips_test',
            onChanged: _onChanged,
            initialValue: [
              Contact('Andrew', '[e-mail]',
                  'https://d2gg9evh47fn9z.cloudfront.net/800px_COLOURBOX4057996.jpg'),
            ],
            maxChips: 5,
            findSuggestions: (String query) {
              if (query.isNotEmpty) {
                var lowercaseQuery = query.toLowerCase();
                return contacts.where((profile) {
                  return profile.name
                          .toLowerCase()
                          .contains(query.toLowerCase()) ||
                      profile.email
                          .toLowerCase()
                          .contains(query.toLowerCase());
                }).toList(growable: false)
                  ..sort((a, b) => a.name
                      .toLowerCase()
                      .indexOf(lowercaseQuery)
                      .compareTo(b.name
                          .toLowerCase()
                          .indexOf(lowercaseQuery)));
              } else {
                return const <Contact>[];
              }
            },
            chipBuilder: (context, state, profile) {
              return InputChip(
                key: ObjectKey(profile),
                label: Text(profile.name),
                avatar: CircleAvatar(
                  backgroundImage: NetworkImage(profile.imageUrl),
                ),
                onDeleted: () => state.deleteChip(profile),
                materialTapTargetSize: MaterialTapTargetSize.shrinkWrap,
              );
            },
            suggestionBuilder: (context, state, profile) {
              return ListTile(
                key: ObjectKey(profile),
                leading: CircleAvatar(
                  backgroundImage: NetworkImage(profile.imageUrl),
                ),
                title: Text(profile.name),
                subtitle: Text(profile.email),
                onTap: () => state.selectSuggestion(profile),
              );
            },
          ),
          FormBuilderDateTimePicker(
            attribute: 'date',
            // onChanged: _onChanged,
            inputType: InputType.time,
            decoration: InputDecoration(
              labelText: 'Appointment Time',
            ),
            initialTime: TimeOfDay(hour: 8, minute: 0),
            // initialValue: DateTime.now(),
            // readonly: true,
          ),
          FormBuilderDateRangePicker(
            attribute: '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(
            attribute: '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(
            attribute: '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),
                    recognizer: TapGestureRecognizer()
                      ..onTap = () {
                        print('launch url');
                      },
                  ),
                ],
              ),
            ),
            validator: FormBuilderValidators.compose([
              FormBuilderValidators.requireTrue(
                context,
                errorText:
                    'You must accept terms and conditions to continue',
              ),
            ]),
          ),
          FormBuilderTextField(
            attribute: '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(
            attribute: '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('$gender'),
                    ))
                .toList(),
          ),
          FormBuilderTypeAhead(
            decoration: InputDecoration(
              labelText: 'Country',
            ),
            attribute: 'country',
            onChanged: _onChanged,
            itemBuilder: (context, country) {
              return ListTile(
                title: Text(country),
              );
            },
            controller: TextEditingController(text: ''),
            initialValue: 'Uganda',
            suggestionsCallback: (query) {
              if (query.isNotEmpty) {
                var lowercaseQuery = query.toLowerCase();
                return allCountries.where((country) {
                  return country.toLowerCase().contains(lowercaseQuery);
                }).toList(growable: false)
                  ..sort((a, b) => a
                      .toLowerCase()
                      .indexOf(lowercaseQuery)
                      .compareTo(
                          b.toLowerCase().indexOf(lowercaseQuery)));
              } else {
                return allCountries;
              }
            },
          ),
          FormBuilderRadioList(
            decoration:
                InputDecoration(labelText: 'My chosen language'),
            attribute: 'best_language',
            onChanged: _onChanged,
            validator: FormBuilderValidators.compose(
                [FormBuilderValidators.required(context)]),
            options: ['Dart', 'Kotlin', 'Java', 'Swift', 'Objective-C']
                .map((lang) => FormBuilderFieldOption(
                      value: lang,
                      child: Text('$lang'),
                    ))
                .toList(growable: false),
          ),
          FormBuilderTouchSpin(
            decoration: InputDecoration(labelText: 'Stepper'),
            attribute: 'stepper',
            initialValue: 10,
            step: 1,
            iconSize: 48.0,
            addIcon: Icon(Icons.arrow_right),
            subtractIcon: Icon(Icons.arrow_left),
          ),
          FormBuilderRating(
            decoration: InputDecoration(labelText: 'Rate this form'),
            attribute: 'rate',
            iconSize: 32.0,
            initialValue: 1.0,
            max: 5.0,
            onChanged: _onChanged,
          ),
        ],
      ),
    ),
    Row(
      children: <Widget>[
        Expanded(
          child: MaterialButton(
            color: Theme.of(context).accentColor,
            child: Text(
              "Submit",
              style: TextStyle(color: Colors.white),
            ),
            onPressed: () {
              _fbKey.currentState.save();
              if (_fbKey.currentState.validate()) {
                print(_fbKey.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: () {
              _fbKey.currentState.reset();
            },
          ),
        ),
      ],
    )
  ],
)

l10n

Just add the FormBuilderLocalizations.delegate in the list of your app delegates

  return MaterialApp(
      supportedLocales: [
        Locale('en'),
        Locale('it'),
        Locale('fr'),
        Locale('es'),
      ],
      localizationsDelegates: [
        FormBuilderLocalizations.delegate,
        GlobalMaterialLocalizations.delegate,
        GlobalWidgetsLocalizations.delegate,
      ],

Input widgets

The currently supported fields include:

• FormBuilderCheckbox - Single Checkbox field
• FormBuilderCheckboxList - List of Checkboxes for multiple selection
• FormBuilderChipsInput - Takes a list of Chips as input and suggests more options on typing
• FormBuilderChoiceChip - Creates a chip that acts like a radio button.
• FormBuilderColorPicker - For Color input selection
• FormBuilderCountryPicker - Country selection from list
• 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.
• FormBuilderImagePicker - Picker a image from Gallery or Camera and stores it in a List of images, File or String. Note: This picker is available for iOS and Android.
• FormBuilderPhoneField - International phone number input.
• FormBuilderRadio - Used to select one value from a list of Radio Widgets
• FormBuilderRadioGroup - Used to select one value from a list of Radio Widgets
• FormBuilderRangeSlider - Used to select a range from a range of values
• FormBuilderRating - For selection of a numerical value as a rating
• FormBuilderSegmentedControl - For selection of a value from the CupertinoSegmentedControl as an input
• FormBuilderSignaturePad - Presents a drawing pad on which user can doodle
• FormBuilderSlider - For selection of a numerical value on a slider
• FormBuilderSwitch - On/Off switch
• FormBuilderTextField - For text input. Accepts input of single-line text, multi-line text, password, email, urls etc by using different configurations and validators
• FormBuilderTouchSpin - Selection of a number by tapping on a plus or minus icon
• FormBuilderTypeAhead - Auto-completes user input from a list of items

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
attribute	String	null	true	This will form the key in the form value Map
initialValue	dynamic	null	false	The initial value of the input field
readOnly	bool	false	false	Determines whether the field widget will accept user input. This value will be ignored if the readOnly attribute of FormBuilder widget is set to true
decoration	InputDecoration	InputDecoration()	false
validator	FormFieldValidator	null	false	A FormFieldValidator that will check the validity of value in the FormField
onChanged	ValueChanged<T>	null	false	This event function will fire immediately the the field value changes
valueTransformer	ValueTransformer<T>	null	false	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.

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(
  attribute: "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]);
          },
        ),
      ),
    );
  },
),

Validation

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.

Built-in Validators

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 in English but with ability to include you own error message that will display whenever validation fails.

Available built-in validators include:

• FormBuilderValidators.required() - requires the field have a non-empty value.
• FormBuilderValidators.numeric() - requires the field's value to be a valid number.
• FormBuilderValidators.min() - requires the field's value to be greater than or equal to the provided number.
• FormBuilderValidators.max() - requires the field's value to be less 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.maxLength() - requires the length of the field's value to be less than or equal to the provided maximum length.
• FormBuilderValidators.pattern() - requires the field's value to match the provided regex pattern.
• FormBuilderValidators.email() - requires the field's value to be a valid email address.
• FormBuilderValidators.url() - requires the field's value to be a valid url.
• FormBuilderValidators.IP() - requires the field's value to be a valid IP address.
• 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.requiredTrue() - requires the field's value be true.

Using multiple validators

FormBuilderValidators class comes with a very useful static function named compose() which takes in 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(
  attribute: "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;
    }
  ]),
),

Programmatically inducing an error

Declare a variable to hold your error:

String _emailError;

Use the variable as the errorText within InputDecoration

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

CREDITS

Contributors

Made with contributors-img.

Dependencies

This package is dependent on the following packages and plugins:

• country_code_picker by
• date_range_picker by anicdh
• datetime_picker_formfield by Jacob Phillips
• flutter_colorpicker by mchome
• flutter_typeahead by AbdulRahmanAlHamali
• phone_number by
• rating_bar by Joshua Matta
• signature by 4Q s.r.o.
• validators by dart-league
• flutter_chips_input & flutter_touch_spin by Yours truly :-)

SUPPORT

PRs

Any kind of support in the form of Pull Requests are always appreciated.

We especially welcome efforts to internationalize/localize the package by translating the default validation error texts.

Coffee :-)

If this package was helpful to you in delivering your project or you just wanna to support this project, a cup of coffee would be highly appreciated ;-)