Isar Link Demo

main.dart

import 'package:flutter/material.dart';
import 'package:isar/isar.dart';
import 'package:path_provider/path_provider.dart';

part 'main.g.dart';

@Collection()
class Teacher {
  int? id;

  late String subject;
}

@Collection()
class Student {
  int? id;

  late String name;

  final teachers = IsarLink<Teacher>();

  @override
  String toString() {
    return 'Student{id: $id, name: $name, teachers: ${teachers.value}}';
  }
}

late final Isar isar;

void main() async {
  WidgetsFlutterBinding.ensureInitialized();

  final dir = await getApplicationSupportDirectory();

  isar = await Isar.open(
    schemas: [TeacherSchema, StudentSchema],
    directory: dir.path,
  );

  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Isar Link Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: const MyHomePage(title: 'Flutter Isar Link Demo'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({Key? key, required this.title}) : super(key: key);

  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _count = 0;

  void _incrementCounter() async {
    final count = _count++;
    final mathTeacher = Teacher()
      ..id = 0
      ..subject = 'Math $count';

    final linda = Student()
      ..id = 0
      ..name = 'Linda $count'
      ..teachers.value = mathTeacher;

    await isar.writeTxn((isar) async {
      await isar.students.put(linda);
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
        actions: [
          IconButton(
            onPressed: () => isar.writeTxn((isar) => isar.clear()).then((_) => _count = 0),
            icon: const Icon(Icons.clear),
          ),
        ],
      ),
      body: Center(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            StreamBuilder<Student?>(
              stream: isar.students.watchObject(0, initialReturn: true),
              builder: (context, snapshot) {
                return Row(
                  mainAxisSize: MainAxisSize.min,
                  children: [
                    const Text('Student: '),
                    Text(snapshot.data?.toString() ?? 'No Data'),
                  ],
                );
              },
            ),
            StreamBuilder<Teacher?>(
              stream: isar.teachers.watchObject(0, initialReturn: true),
              builder: (context, snapshot) {
                return Row(
                  mainAxisSize: MainAxisSize.min,
                  children: [
                    const Text('Teacher: '),
                    Text(snapshot.data?.toString() ?? 'No Data'),
                  ],
                );
              },
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: const Icon(Icons.add),
      ),
    );
  }
}