Skip to main content
Version: Current

Quick Start

This page contains information to quickly get Realm Database integrated into your Flutter app.

Before you begin, ensure you have:

Local Realm Database Only

The Flutter SDK currently only supports local Realm Database. You cannot use the Flutter SDK to connect to MongoDB Realm application services or use Realm Sync.

Define Your Object Model​

Your application's data model defines the structure of data stored within Realm Database. You can define your application's data model via Dart classes in your application code with Realm Object Models. You then have to generate the RealmObject class that's used within your application.

Create Data Model​

To define your application's data model, add a Realm model class definition to your application code.

Some considerations when defining your Realm model class:

  • Import package at the top of your class definition file.
  • In your file, give your class a private name (starting with _), such as a file car.dart with a class _Car. You generate the public RealmObject class using the command in the Generate RealmObject Class section. This command outputs a public class, such as Car.
  • Make sure to include the generated file name, such as part car.g.dart, before the code defining your model. This is required to generate the RealmObject class.
import 'package:realm/realm.dart';

part 'car.g.dart';

@RealmModel()
class _Car {
  @PrimaryKey()
  late final String make;

  late String? model;
  late int? miles;
}

Generate RealmObject Class​

Now generate a RealmObject class Car from the data model class Car:

flutter pub run realm generate

Running this creates a Car class in a car.g.dart file located in the directory where you defined the model class per the above Create Data Model section. This Car class is public and part of the same library as the _Car data model class. The generated Car class is what's used throughout your application.

If you'd like to watch your data model class to generate a new Car class whenever there's a change to _Car, run:

flutter pub run realm generate --watch

Open a Realm​

Use the Configuration class to control the specifics of the realm you would like to open, including schema.

Pass your configuration to the Realm constructor to generate an instance of that realm:

var config = Configuration([Car.schema]);
var realm = Realm(config);

You can now use that realm instance to work with objects in the database.

Work with Realm Objects​

Once you've opened a realm, you can create objects within it using a write transaction block.

Create Objects​

To create a new Car, instantiate an instance of the Car class and add it to the realm in a write transaction block:

final car = Car('Tesla', model: 'Model S', miles: 42);
realm.write(() {
  realm.add(car);
});

Update Objects​

To modify a car, update its properties in a write transaction block:

realm.write(() {
  car.miles = 99;
});

Query for Objects​

Retrieve a collection of all objects of a data model in the realm with the Realm.all() method:

var cars = realm.all<Car>();
var myCar = cars[0];
print('My car is ${myCar.make} ${myCar.model}');

Filter a collection to retrieve a specific segment of objects with the Realm.query() method:

var cars = realm.all<Car>();
var myCar = cars[0];
print('My car is ${myCar.make} ${myCar.model}');

Sort the results using NSPredicate syntax:

realm.write(() {
  realm.add(Car('BMW', model: 'Z4', miles: 42));
  realm.add(Car('Audi', model: 'A8', miles: 99));
  realm.add(Car('Mercedes', model: 'G-Wagon', miles: 2));
});
final sortedCars = realm.query<Car>('TRUEPREDICATE SORT(model ASC)');
for (var car in sortedCars) {
  print(car.model);
}
// prints 'A8', 'G-Wagon', 'Z4'

Delete Objects​

Delete a car by calling the Realm.delete() method in a write transaction block:

realm.write(() {
  realm.delete(car);
});

Delete multiple cars with the Realm.deleteMany() method in a write transaction block.

realm.write(() {
  realm.deleteMany(cars);
});

Close a Realm​

Once you've finished working with a realm, close it to prevent memory leaks.

realm.close();

Further Examples​

For further examples of all the Flutter SDK methods described above and more, refer to the Realm Dart Samples Github repo.