MultiSelect Widget

main.dart

// Needed: add http: as dependency

import 'dart:convert';

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:http/http.dart';

void main() {
  runApp(App());
}

class App extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Multi Select Widget',
      home: MultiSelectWidget(),
    );
  }
}

class MultiSelectWidget extends StatefulWidget {
  @override
  _MultiSelectWidgetState createState() => _MultiSelectWidgetState();
}

class _MultiSelectWidgetState extends State<MultiSelectWidget> {
  Language language;
  Map<String, LanguageData> selectedLanguage;

  @override
  void initState() {
    super.initState();
    selectedLanguage = {};
    WidgetsBinding.instance.addPostFrameCallback((_) {
      get('http://rashmikotian.com/artist/api/artists/index').then((result) {
        language = Language.fromJson(json.decode(result.body));
        setState(() {});
      }).catchError((e) {
        print(e);
      });
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Multi Select Widget'),
        actions: [
          IconButton(
            onPressed: () {
              if (selectedLanguage.length != language.languageData.length) {
                language.languageData.forEach((each) {
                  selectedLanguage[each.hashCode.toString()] = each;
                });
              } else {
                selectedLanguage.clear();
              }
              setState(() {});
            },
            icon: Icon(Icons.swap_horiz),
          )
        ],
      ),
      body: Builder(
        builder: (_) {
          if (language == null) {
            return Center(child: CircularProgressIndicator());
          } else {
            return ListView.builder(
              itemBuilder: (context, index) {
                return ListTile(
                    title:
                        Text(language.languageData[index].toJson().toString()),
                    trailing: IconButton(
                      onPressed: () {
                        if (!selectedLanguage.containsKey(
                            language.languageData[index].hashCode.toString())) {
                          selectedLanguage[language.languageData[index].hashCode
                              .toString()] = language.languageData[index];
                        } else {
                          selectedLanguage.remove(
                              language.languageData[index].hashCode.toString());
                        }
                        setState(() {});
                      },
                      icon: Builder(
                        builder: (_) {
                          if (selectedLanguage.containsKey(language
                              .languageData[index].hashCode
                              .toString())) {
                            return Icon(Icons.check_box);
                          } else
                            return Icon(Icons.check_box_outline_blank);
                        },
                      ),
                    ));
              },
              itemCount: language.languageData.length,
            );
          }
        },
      ),
    );
  }
}

class Language {
  List<LanguageData> languageData;
  List<TagsData> tagsData;
  List<WorkPreferenceData> workPreferenceData;

  Language({this.languageData, this.tagsData, this.workPreferenceData});

  Language.fromJson(Map<String, dynamic> json) {
    if (json['language_data'] != null) {
      languageData = new List<LanguageData>();
      json['language_data'].forEach((v) {
        languageData.add(new LanguageData.fromJson(v));
      });
    }
    if (json['tags_data'] != null) {
      tagsData = new List<TagsData>();
      json['tags_data'].forEach((v) {
        tagsData.add(new TagsData.fromJson(v));
      });
    }
    if (json['work_preference_data'] != null) {
      workPreferenceData = new List<WorkPreferenceData>();
      json['work_preference_data'].forEach((v) {
        workPreferenceData.add(new WorkPreferenceData.fromJson(v));
      });
    }
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    if (this.languageData != null) {
      data['language_data'] = this.languageData.map((v) => v.toJson()).toList();
    }
    if (this.tagsData != null) {
      data['tags_data'] = this.tagsData.map((v) => v.toJson()).toList();
    }
    if (this.workPreferenceData != null) {
      data['work_preference_data'] =
          this.workPreferenceData.map((v) => v.toJson()).toList();
    }
    return data;
  }
}

class LanguageData {
  String id;
  String name;
  String createdOn;
  String modifiedOn;
  String createdBy;
  String modifiedBy;
  String status;

  LanguageData(
      {this.id,
      this.name,
      this.createdOn,
      this.modifiedOn,
      this.createdBy,
      this.modifiedBy,
      this.status});

  LanguageData.fromJson(Map<String, dynamic> json) {
    id = json['id'];
    name = json['name'];
    createdOn = json['created_on'];
    modifiedOn = json['modified_on'];
    createdBy = json['created_by'];
    modifiedBy = json['modified_by'];
    status = json['status'];
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    data['id'] = this.id;
    data['name'] = this.name;
    data['created_on'] = this.createdOn;
    data['modified_on'] = this.modifiedOn;
    data['created_by'] = this.createdBy;
    data['modified_by'] = this.modifiedBy;
    data['status'] = this.status;
    return data;
  }
}

class TagsData {
  String id;
  String name;
  String createdOn;
  String modifiedOn;
  String createdBy;
  String modifiedBy;
  String status;

  TagsData(
      {this.id,
      this.name,
      this.createdOn,
      this.modifiedOn,
      this.createdBy,
      this.modifiedBy,
      this.status});

  TagsData.fromJson(Map<String, dynamic> json) {
    id = json['id'];
    name = json['name'];
    createdOn = json['created_on'];
    modifiedOn = json['modified_on'];
    createdBy = json['created_by'];
    modifiedBy = json['modified_by'];
    status = json['status'];
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    data['id'] = this.id;
    data['name'] = this.name;
    data['created_on'] = this.createdOn;
    data['modified_on'] = this.modifiedOn;
    data['created_by'] = this.createdBy;
    data['modified_by'] = this.modifiedBy;
    data['status'] = this.status;
    return data;
  }
}

class WorkPreferenceData {
  String id;
  String name;

  WorkPreferenceData({this.id, this.name});

  WorkPreferenceData.fromJson(Map<String, dynamic> json) {
    id = json['id'];
    name = json['name'];
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    data['id'] = this.id;
    data['name'] = this.name;
    return data;
  }
}