Local database

Work Offline with Local Database

Want your Flutter app to work even when there's no internet? A local database is the answer! This guide shows you how to set one up using the Drift package.

1 - Get the Drift Package

First, you need to add the necessary packages to your project. Open your terminal in your project folder and run these commands:

dart pub add drift
dart pub add drift_flutter
dart pub add drift_dev

This adds the main drift package, one for Flutter integration, and one for development tools (like code generation).

2 - Set Up Your Database

Create a Dart file for your database. You'll define a class that extends _$Database. Use the @DriftDatabase annotation to tell Drift which tables belong to this database.

@DriftDatabase(tables: [
  TaskTable,
])
class Database extends _$Database {
  Database([QueryExecutor? e]) : super(
    e ??
      DriftDatabase(
        name: 'todo-app',
        native: const DriftNativeOptions(
          databaseDirectory: getApplicationSupportDirectory,
        ),
      ),
  );

  @override
  int get schemaVersion => 2; // Your database version

  @override
  MigrationStrategy get migration {
    return MigrationStrategy(
      onCreate: (m) async {
        await m.createAll();
      },
      // Push any migration here if version is new
    );
  }
}

This code sets up your database with a specific name and location, defines its schema version, and handles initial creation.

3 - Define Your Tables

Each table in your database needs a corresponding Dart class that extends Table. Use the @DataClassName annotation to give the generated data class a custom name (like 'TaskEntry' for 'TaskTable'). Define your columns using types like IntColumn and TextColumn.

@DataClassName('TaskEntry')
class TaskTable extends Table {
  IntColumn get id => integer().autoIncrement()();
  TextColumn get description => text()();

  // Add your queries like this
  static Stream<List<TaskEntry>> getAllItems(Database database) =>
      database.select(database.taskTable).watch();
}

You can also add static methods here to define common queries for your table.

4 - Configure the Build File

Drift uses code generation to create a lot of the necessary code for you. You need to configure the build.yaml file at the root of your Flutter project to tell the build runner where to find your database definition.

targets:
  $default:
    builders:
      ## Add this
      drift_dev:
        # These options change how drift generates code
        options:
          databases:
            default: lib/modules/drift/database.dart
            sql:
              dialect: sqlite
              options:
                version: "3.38"
                modules: [fts5]

After setting this up, you need to run the build runner command to generate the database schema and other necessary code.

Run the Build Runner

Make sure to run this command in your project directory whenever you make changes to your database or tables:

Build Runner Command

dart run build_runner build

This command generates the code needed to interact with your database based on your definitions.