Lära SQLite with Drift | Local Storage

Definition

SQLite is a lightweight, embedded database engine that is widely used for managing structured data directly on a device.

In Flutter, using SQLite directly can be verbose and error-prone, especially when handling data models and queries. Drift is an Object-Relational Mapping (ORM) library for Dart that simplifies working with SQLite by providing type-safe APIs, automatic code generation, and support for reactive data streams. By using Drift, you can define your database tables as Dart classes, write queries in a more natural way, and react to changes in your data efficiently.

main.dart


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// main.dart
import 'package:drift/drift.dart';
import 'package:drift/native.dart';
import 'dart:io';
import 'package:path/path.dart' as p;
import 'package:path_provider/path_provider.dart';

// Define a table
class Todos extends Table {
  IntColumn get id => integer().autoIncrement()();
  TextColumn get title => text()();
  BoolColumn get completed => boolean().withDefault(const Constant(false))();
}

// Create a database class
@DriftDatabase(tables: [Todos])
class AppDatabase extends _$AppDatabase {
  AppDatabase() : super(_openConnection());

  @override
  int get schemaVersion => 1;
}

// Open the database connection
LazyDatabase _openConnection() {
  return LazyDatabase(() async {
    final dbFolder = await getApplicationDocumentsDirectory();
    final file = File(p.join(dbFolder.path, 'db.sqlite'));
    return NativeDatabase(file);
  });
}

// Example usage: insert a todo
Future<void> main() async {
  final db = AppDatabase();
  final id = await db.into(db.todos).insert(
    TodosCompanion.insert(title: 'Learn Drift ORM'),
  );
  print('Inserted todo with id: $id');
  await db.close();
}

With Drift, querying the database becomes type-safe and concise. You can easily fetch records using generated APIs, and Drift supports reactive streams, so your UI can automatically update when the underlying data changes. For example, you can watch a table or a specific query and rebuild widgets in response to updates, making state management with local databases straightforward and robust.

main.dart


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import 'package:drift/drift.dart';
import 'package:drift/native.dart';
import 'dart:io';
import 'package:path/path.dart' as p;
import 'package:path_provider/path_provider.dart';

class Todos extends Table {
  IntColumn get id => integer().autoIncrement()();
  TextColumn get title => text()();
  BoolColumn get completed => boolean().withDefault(const Constant(false))();
}

@DriftDatabase(tables: [Todos])
class AppDatabase extends _$AppDatabase {
  AppDatabase() : super(_openConnection());

  @override
  int get schemaVersion => 1;
}

LazyDatabase _openConnection() {
  return LazyDatabase(() async {
    final dbFolder = await getApplicationDocumentsDirectory();
    final file = File(p.join(dbFolder.path, 'db.sqlite'));
    return NativeDatabase(file);
  });
}

// Example usage: update a todo
Future<void> main() async {
  final db = AppDatabase();
  // Insert a todo first
  final id = await db.into(db.todos).insert(
    TodosCompanion.insert(title: 'Update Drift record'),
  );
  // Update the todo's completed status
  await (db.update(db.todos)..where((t) => t.id.equals(id))).write(
    TodosCompanion(completed: Value(true)),
  );
  print('Updated todo with id: $id');
  await db.close();
}

Var allt tydligt?

Tack för dina kommentarer!

Avsnitt 3. Kapitel 3

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Definition

SQLite is a lightweight, embedded database engine that is widely used for managing structured data directly on a device.

main.dart


              1234567891011121314151617181920212223242526272829303132333435363738394041
            
// main.dart
import 'package:drift/drift.dart';
import 'package:drift/native.dart';
import 'dart:io';
import 'package:path/path.dart' as p;
import 'package:path_provider/path_provider.dart';

// Define a table
class Todos extends Table {
  IntColumn get id => integer().autoIncrement()();
  TextColumn get title => text()();
  BoolColumn get completed => boolean().withDefault(const Constant(false))();
}

// Create a database class
@DriftDatabase(tables: [Todos])
class AppDatabase extends _$AppDatabase {
  AppDatabase() : super(_openConnection());

  @override
  int get schemaVersion => 1;
}

// Open the database connection
LazyDatabase _openConnection() {
  return LazyDatabase(() async {
    final dbFolder = await getApplicationDocumentsDirectory();
    final file = File(p.join(dbFolder.path, 'db.sqlite'));
    return NativeDatabase(file);
  });
}

// Example usage: insert a todo
Future<void> main() async {
  final db = AppDatabase();
  final id = await db.into(db.todos).insert(
    TodosCompanion.insert(title: 'Learn Drift ORM'),
  );
  print('Inserted todo with id: $id');
  await db.close();
}

main.dart


              123456789101112131415161718192021222324252627282930313233343536373839404142
            
import 'package:drift/drift.dart';
import 'package:drift/native.dart';
import 'dart:io';
import 'package:path/path.dart' as p;
import 'package:path_provider/path_provider.dart';

class Todos extends Table {
  IntColumn get id => integer().autoIncrement()();
  TextColumn get title => text()();
  BoolColumn get completed => boolean().withDefault(const Constant(false))();
}

@DriftDatabase(tables: [Todos])
class AppDatabase extends _$AppDatabase {
  AppDatabase() : super(_openConnection());

  @override
  int get schemaVersion => 1;
}

LazyDatabase _openConnection() {
  return LazyDatabase(() async {
    final dbFolder = await getApplicationDocumentsDirectory();
    final file = File(p.join(dbFolder.path, 'db.sqlite'));
    return NativeDatabase(file);
  });
}

// Example usage: update a todo
Future<void> main() async {
  final db = AppDatabase();
  // Insert a todo first
  final id = await db.into(db.todos).insert(
    TodosCompanion.insert(title: 'Update Drift record'),
  );
  // Update the todo's completed status
  await (db.update(db.todos)..where((t) => t.id.equals(id))).write(
    TodosCompanion(completed: Value(true)),
  );
  print('Updated todo with id: $id');
  await db.close();
}

Var allt tydligt?

Tack för dina kommentarer!

Avsnitt 3. Kapitel 3