Getting Started¶

1. Setup Dependencies¶

Add the runtime dependency floor as well as the generator floor_generator to your pubspec.yaml. The third dependency is build_runner which has to be included as a dev dependency just like the generator.

floor holds all the code you are going to use in your application.
floor_generator includes the code for generating the database classes.
build_runner enables a concrete way of generating source code files.

dependencies:
  flutter:
    sdk: flutter
  floor: ^1.4.0

dev_dependencies:
  floor_generator: ^1.4.0
  build_runner: ^2.1.2

2. Create an Entity¶

It will represent a database table as well as the scaffold of your business object. @entity marks the class as a persistent class. It's required to add a primary key to your table. You can do so by adding the @primaryKey annotation to an int property. There is no restriction on where you put the file containing the entity.

// entity/person.dart

import 'package:floor/floor.dart';

@entity
class Person {
  @primaryKey
  final int id;

  final String name;

  Person(this.id, this.name);
}

3. Create a DAO (Data Access Object)¶

This component is responsible for managing access to the underlying SQLite database. The abstract class contains the method signatures for querying the database which have to return a Future or Stream.

You can define queries by adding the @Query annotation to a method. The SQL statement has to get added in parenthesis. The method must return a Future or Stream of the Entity you're querying for.
@insert marks a method as an insertion method.

// dao/person_dao.dart

import 'package:floor/floor.dart';

@dao
abstract class PersonDao {
  @Query('SELECT * FROM Person')
  Future<List<Person>> findAllPersons();

  @Query('SELECT * FROM Person WHERE id = :id')
  Stream<Person?> findPersonById(int id);

  @insert
  Future<void> insertPerson(Person person);
}

4. Create the Database¶

It has to be an abstract class which extends FloorDatabase. Furthermore, it's required to add @Database() to the signature of the class. Make sure to add the created entity to the entities attribute of the @Database annotation. In order to make the generated code work, it's required to also add the listed imports.

Make sure to add part 'database.g.dart'; beneath the imports of this file. It's important to note that 'database' has to get exchanged with the filename of the database definition. In this case, the file is named database.dart.

// database.dart

// required package imports
import 'dart:async';
import 'package:floor/floor.dart';
import 'package:sqflite/sqflite.dart' as sqflite;

import 'dao/person_dao.dart';
import 'entity/person.dart';

part 'database.g.dart'; // the generated code will be there

@Database(version: 1, entities: [Person])
abstract class AppDatabase extends FloorDatabase {
  PersonDao get personDao;
}

5. Run the Code Generator¶

Run the generator with flutter packages pub run build_runner build. To automatically run it, whenever a file changes, use flutter packages pub run build_runner watch.

6. Use the Generated Code¶

For obtaining an instance of the database, use the generated $FloorAppDatabase class, which allows access to a database builder. The name is being composed by $Floor and the database class name. The string passed to databaseBuilder() will be the database file name. For initializing the database, call build() and make sure to await the result.

In order to retrieve the PersonDao instance, invoking the persoDao getter on the database instance is enough. Its functions can be used as shown in the following snippet.

final database = await $FloorAppDatabase.databaseBuilder('app_database.db').build();

final personDao = database.personDao;
final person = Person(1, 'Frank');

await personDao.insertPerson(person);
final result = await personDao.findPersonById(1);

For further examples take a look at the example and test directories.