flutter_form_builder 7.0.0-alpha.3

This package helps in creation of forms in Flutter by removing the boilerplate code, reusing validation, react to changes, and collect final user input.

Flutter FormBuilder - 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.

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Example

final _formKey = GlobalKey<FormBuilderState>();

@override
Widget build(BuildContext context) {
  return Column(
    children: <Widget>[
      FormBuilder(
        key: _formKey,
        autovalidate: true,
        child: Column(
          children: <Widget>[
            
          ],
        ),
      ),
      Row(
        children: <Widget>[
          Expanded(
            child: MaterialButton(
              color: Theme.of(context).colorScheme.secondary,
              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).colorScheme.secondary,
              child: Text(
                "Reset",
                style: TextStyle(color: Colors.white),
              ),
              onPressed: () {
                _formKey.currentState.reset();
              },
            ),
          ),
        ],
      ),
    ],
  );
}

FormBuilderField attributes

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.

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(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]);
          },
        ),
      ),
    );
  },
),

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', '[e-mail]', 'https://d2gg9evh47fn9z.cloudfront.net/800px_COLOURBOX4057996.jpg'),
  ],
});

Programmatically inducing an error

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.');
    }
  },
),

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(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;
    },
  ),

Ecosystem

Here are additional packages that you can use to extend flutter_form_builder's functionality.

• form_builder_fields - provides common ready-made form input fields compartible with flutter_form_builder.
• form_builder_validators - provides a convenient way of validating data entered into any Flutter FormField.
• form_builder_extra_fields - provides additional ready-made form input fields compartible with flutter_form_builder.
• form_builder_file_picker - A FormbuilderField that allows selecting image(s) from user device storage.
• form_builder_image_picker - A FormbuilderField that allows selecting image(s) from device Gallery or Camera.
• form_builder_map_field - A FormbuilderField for geographic location input.
• form_builder_phone_field - A FormbuilderField for international phone number input.

Support

Issues and PRs

Any kind of support in the form of reporting bugs, answering questions or PRs is always appreciated.

Coffee :-)

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 ;-)