Local Database Samebase In Flutter

Local Database Samebase In Flutter :

This flutter tutorial post is Local database sembase in flutter. It is support List data insert.

dependencies:
sembast:
path_provider:
flutter_bloc:
equatable:

Screenshot :

Project structure Screenshot :

Model package

-subject.dart

import 'package:meta/meta.dart';

class Subject {
  int id;

  final String name;
  final bool isLike;

  Subject({
    @required this.name,
    @required this.isLike,
  });

  Map<String, dynamic> toMap() {
    return {
      'name': name,
      'isLike': isLike,
    };
  }

  static Subject fromMap(Map<String, dynamic> map) {
    return Subject(
      name: map['name'],
      isLike: map['isLike'],
    );
  }
}

db Package

– app_database.dart

import 'dart:async';

import 'package:path/path.dart';
import 'package:path_provider/path_provider.dart';
import 'package:sembast/sembast.dart';
import 'package:sembast/sembast_io.dart';

class AppDatabase {
  // Singleton instance
  static final AppDatabase _singleton = AppDatabase._();

  // Singleton accessor
  static AppDatabase get instance => _singleton;

  // Completer is used for transforming synchronous code into asynchronous code.
  Completer<Database> _dbOpenCompleter;

  // A private constructor. Allows us to create instances of AppDatabase
  // only from within the AppDatabase class itself.
  AppDatabase._();

  // Sembast database object
  Database _database;

  // Database object accessor
  Future<Database> get database async {
    // If completer is null, AppDatabaseClass is newly instantiated, so database is not yet opened
    if (_dbOpenCompleter == null) {
      _dbOpenCompleter = Completer();
      // Calling _openDatabase will also complete the completer with database instance
      _openDatabase();
    }
    // If the database is already opened, awaiting the future will happen instantly.
    // Otherwise, awaiting the returned future will take some time - until complete() is called
    // on the Completer in _openDatabase() below.
    return _dbOpenCompleter.future;
  }

  Future _openDatabase() async {
    // Get a platform-specific directory where persistent app data can be stored
    final appDocumentDir = await getApplicationDocumentsDirectory();
    // Path with the form: /platform-specific-directory/demo.db
    final dbPath = join(appDocumentDir.path, 'demo.db');

    final database = await databaseFactoryIo.openDatabase(dbPath);
    // Any code awaiting the Completer's future will now start executing
    _dbOpenCompleter.complete(database);
  }
}

subject_dao.dart

import 'package:sembast/sembast.dart';
import 'app_database.dart';
import '../model/subject.dart';

class SubjectDao {
  static const String STORE_NAME = 'subject';
  // A Store with int keys and Map<String, dynamic> values.
  // This Store acts like a persistent map, values of which are subject objects converted to Map
  final _subjectStore = intMapStoreFactory.store(STORE_NAME);

  // Private getter to shorten the amount of code needed to get the
  // singleton instance of an opened database.
  Future<Database> get _db async => await AppDatabase.instance.database;

  Future insert(Subject subject) async {
    await _subjectStore.add(await _db, subject.toMap());
  }

  Future update(Subject subject) async {
    // For filtering by key (ID), RegEx, greater than, and many other criteria,
    // we use a Finder.
    final finder = Finder(filter: Filter.byKey(subject.id));
    await _subjectStore.update(
      await _db,
      subject.toMap(),
      finder: finder,
    );
  }

  Future delete(Subject subject) async {
    final finder = Finder(filter: Filter.byKey(subject.id));
    await _subjectStore.delete(
      await _db,
      finder: finder,
    );
  }

  Future<List<Subject>> getAllSortedByName() async {
    // Finder object can also sort data.
    final finder = Finder(sortOrders: [
      SortOrder('name'),
    ]);

    final recordSnapshots = await _subjectStore.find(
      await _db,
      finder: finder,
    );

    // Making a List<Subject> out of List<RecordSnapshot>
    return recordSnapshots.map((snapshot) {
      final subject = Subject.fromMap(snapshot.value);
      // An ID is a key of a record from the database.
      subject.id = snapshot.key;
      return subject;
    }).toList();
  }
}

Bloc Package

-subject_bloc.dart

import 'dart:async';
import 'dart:math';
import 'package:bloc/bloc.dart';
import '../model/subject.dart';
import '../db/subject_dao.dart';
import 'subject_event.dart';
import 'subject_state.dart';

class SubjectBloc extends Bloc<SubjectEvent, SubjectState> {
  SubjectDao _subjectDao = SubjectDao();

  // Display a loading indicator right from the start of the app
  @override
  SubjectState get initialState =>SubjectLoading();

  // This is where we place the logic.
  @override
  Stream<SubjectState> mapEventToState(
    SubjectEvent event,
  ) async* {
    if (event is Load) {
      // Indicating that subjects are being loaded - display progress indicator.
      yield SubjectLoading();
      yield* _reloadSubjects();
    } else if (event is AddRandomSubject) {
      await _subjectDao.insert(RandomGenerator.getRandomSubject());
      yield* _reloadSubjects();
    } else if (event is UpdateWithRandomSubject) {
      final newSubject = RandomGenerator.getRandomSubject();
      // Keeping the ID of the Subject the same
      newSubject.id = event.updatedSubject.id;
      await _subjectDao.update(newSubject);
      yield* _reloadSubjects();
    } else if (event is DeleteSubject) {
      await _subjectDao.delete(event.subject);
      yield* _reloadSubjects();
    }
  }

  Stream<SubjectState> _reloadSubjects() async* {
    final subjects = await _subjectDao.getAllSortedByName();
    // Yielding a state bundled with the Subjects from the database.
    yield SubjectLoaded(subjects);
  }
}

class RandomGenerator {
  static final _subjects = [
    Subject(name: 'Java', isLike: true),
    Subject(name: 'Android', isLike: true),
    Subject(name: 'Flutter', isLike: false),
    Subject(name: 'PHP', isLike: true),
    Subject(name: 'C', isLike: true),
    Subject(name: 'C++', isLike: false),
  ];

  static Subject getRandomSubject() {
    return _subjects[Random().nextInt(_subjects.length)];
  }
}

subject_event.dart

import 'package:equatable/equatable.dart';
import 'package:meta/meta.dart';
import '../model/subject.dart';

@immutable
abstract class SubjectEvent extends Equatable {
  SubjectEvent([List props = const []]) : super(props);
}

class Load extends SubjectEvent {}

class AddRandomSubject extends SubjectEvent {}

class UpdateWithRandomSubject extends SubjectEvent {
  final Subject updatedSubject;

  UpdateWithRandomSubject(this.updatedSubject) : super([updatedSubject]);
}

class DeleteSubject extends SubjectEvent {
  final Subject subject;

  DeleteSubject(this.subject) : super([subject]);
}

subject_state.dart

import 'package:equatable/equatable.dart';
import 'package:meta/meta.dart';

import '../model/subject.dart';

@immutable
abstract class SubjectState extends Equatable {
  SubjectState([List props = const []]) : super(props);
}

class SubjectLoading extends SubjectState {}

class SubjectLoaded extends SubjectState {
  final List<Subject> subjects;

  SubjectLoaded(this.subjects) : super([subjects]);
}

home_page.dart

import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'bloc/subject_event.dart';
import 'model/subject.dart';
import 'bloc/subject_bloc.dart';
import 'bloc/subject_state.dart';

class HomePage extends StatefulWidget {
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  SubjectBloc _subjectBloc;

  @override
  void initState() {
    super.initState();
    _subjectBloc = BlocProvider.of<SubjectBloc>(context);
    _subjectBloc.dispatch(Load());
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('SEMBAST DATABASE'),
      ),
      body: _buildBody(),
      floatingActionButton: FloatingActionButton(
        child: Icon(Icons.add),
        onPressed: () {
          _subjectBloc.dispatch(AddRandomSubject());
        },
      ),
    );
  }

  Widget _buildBody() {
    return BlocBuilder(
      bloc: _subjectBloc,
      // Whenever there is a new state emitted from the bloc, builder runs.
      builder: (BuildContext context, SubjectState state) {
        if (state is SubjectLoading) {
          return Center(
            child: CircularProgressIndicator(),
          );
        } else if (state is SubjectLoaded) {
          return ListView.builder(
            itemCount: state.subjects.length,
            itemBuilder: (context, index) {
              final displayed = state.subjects[index];
              return ListTile(
                title: Text(displayed.name),
                subtitle:
                    Text(displayed.isLike ? 'Like!' : 'Sooo sour!'),
                trailing: _buildUpdateDeleteButtons(displayed),
              );
            },
          );
        }
        return Container();
      },
    );
  }

  Row _buildUpdateDeleteButtons(Subject subject) {
    return Row(
      mainAxisSize: MainAxisSize.min,
      children: <Widget>[
        IconButton(
          icon: Icon(Icons.refresh),
          onPressed: () {
            _subjectBloc.dispatch(UpdateWithRandomSubject(subject));
          },
        ),
        IconButton(
          icon: Icon(Icons.delete_outline),
          onPressed: () {
            _subjectBloc.dispatch(DeleteSubject(subject));
          },
        ),
      ],
    );
  }
}

main.dart

import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';

import 'bloc/subject_bloc.dart';
import 'home_page.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return BlocProvider(
      builder: (context) => SubjectBloc(),
      child: MaterialApp(
        title: 'Flutter Tutorial',
        theme: ThemeData(
          primarySwatch: Colors.blue,
          accentColor: Colors.blue,
        ),
        home: HomePage(),
      ),
    );
  }
}

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