Multi select form field using alert dialog in flutter

A multi select form field using alert dialog to select multiple items with checkboxes and showing as chips.

Features

• Can be used as regular form field.
• Simple to implement.
• Simple and intuitive to use in the app.
• Provides validation of data.
• Provides requirement of the field.
• Customizable texts.
• Follows the app theme and colors.

Customization Parameters [MultiFormField]

Parameter	Description
title Widget	Set Title of MultiSelectTextFormField.
hintWidget Widget	Set Hint Text of MultiSelectTextFormField.
required bool	Add Selection is Compulsary or not.
errorText String	Error String to be Displayed
dataSource List	List of Data as DataSource To Select.
textField String	Key Param from List (DataSource).
valueField String	Value Param From List (DataSource).
okButtonLabel String*	POsitive Button Label String.
cancelButtonLabel String*	Negative Button Label String.
fillColor Color Widget	Changes background color of FormField

Customization [Selection Dialog]

Parameter	Description
Shape ShapeBorder	Customizes the Shape Of AlertDialog
dialogTextStyle TextStyle	Customizes the TextStyle Of AlertDialog
checkBoxCheckColor Color	Customizes the CheckColor
checkBoxActiveColor Color	Customizes the CheckBoxActiveColor

Customization [Selection Chip]

Parameter	Description
chipLabelStyle TextStyle	Customizes the TextStyle Of Selected Chip
chipBackGroundColor Color	Customizes the Color Of Selected Chip

Minimal Example

MultiSelectFormField(
                  autovalidate: false,
                  chipBackGroundColor: Colors.red,
                  chipLabelStyle: TextStyle(fontWeight: FontWeight.bold),
                  dialogTextStyle: TextStyle(fontWeight: FontWeight.bold),
                  checkBoxActiveColor: Colors.red,
                  checkBoxCheckColor: Colors.green,
                  dialogShapeBorder: RoundedRectangleBorder(
                      borderRadius: BorderRadius.all(Radius.circular(12.0))),
                  title: Text(
                    "Title Of Form",
                    style: TextStyle(fontSize: 16),
                  ),
                  dataSource: [
                    {
                      "display": "Running",
                      "value": "Running",
                    },
                    {
                      "display": "Climbing",
                      "value": "Climbing",
                    },
                    {
                      "display": "Walking",
                      "value": "Walking",
                    },
                  ],
                  textField: 'display',
                  valueField: 'value',
                  okButtonLabel: 'OK',
                  cancelButtonLabel: 'CANCEL',
                  hintWidget: Text('Please choose one or more'),
                  initialValue: _myActivities,
                  onSaved: (value) {
                    if (value == null) return;
                    setState(() {
                      _myActivities = value;
                    });
                  },
                ),

Example

import 'package:multiselect_formfield/multiselect_formfield.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  List _myActivities;
  String _myActivitiesResult;
  final formKey = new GlobalKey<FormState>();

  @override
  void initState() {
    super.initState();
    _myActivities = [];
    _myActivitiesResult = '';
  }

  _saveForm() {
    var form = formKey.currentState;
    if (form.validate()) {
      form.save();
      setState(() {
        _myActivitiesResult = _myActivities.toString();
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('MultiSelect Formfield Example'),
      ),
      body: Center(
        child: Form(
          key: formKey,
          child: Column(
            mainAxisAlignment: MainAxisAlignment.start,
            children: <Widget>[
              Container(
                padding: EdgeInsets.all(16),
                child: MultiSelectFormField(
                  autovalidate: false,
                  titleText: 'My workouts',
                  validator: (value) {
                    if (value == null || value.length == 0) {
                      return 'Please select one or more options';
                    }
                  },
                  dataSource: [
                    {
                      "display": "Running",
                      "value": "Running",
                    },
                    {
                      "display": "Climbing",
                      "value": "Climbing",
                    },
                    {
                      "display": "Walking",
                      "value": "Walking",
                    },
                    {
                      "display": "Swimming",
                      "value": "Swimming",
                    },
                    {
                      "display": "Soccer Practice",
                      "value": "Soccer Practice",
                    },
                    {
                      "display": "Baseball Practice",
                      "value": "Baseball Practice",
                    },
                    {
                      "display": "Football Practice",
                      "value": "Football Practice",
                    },
                  ],
                  textField: 'display',
                  valueField: 'value',
                  okButtonLabel: 'OK',
                  cancelButtonLabel: 'CANCEL',
                  // required: true,
                  hintText: 'Please choose one or more',
                  value: _myActivities,
                  onSaved: (value) {
                    if (value == null) return;
                    setState(() {
                      _myActivities = value;
                    });
                  },
                ),
              ),
              Container(
                padding: EdgeInsets.all(8),                
                child: RaisedButton(
                  child: Text('Save'),
                  onPressed: _saveForm,
                ),
              ),
              Container(
                padding: EdgeInsets.all(16),
                child: Text(_myActivitiesResult),
              )
            ],
          ),
        ),
      ),
    );
  }
}

Demo