Typed Data

Description — How to Access Strongly Typed Data in a Type Safe Manner

caution

The typed data API is experimental and might be missing some feature that you need. Please file an issue if you find a bug or have a feature request.

Couchbase Lite allows dynamic access to data without a fixed data model, not requiring any code generation. This is useful when the data is very dynamic or code generation is undesirable.

Often though, the data is known to have a regular structure, and accessing it through a typed Dart API makes working with it easier and safer.

With the help of the cbl_generator package you can quickly create Dart classes that can be used to access data in a typed way. Theses classes can be used with specialized APIs of Database, Query and Replicator.

Getting started

Make sure your app is setup for using Couchbase Lite.

Add cbl_generator and build_runner as development dependencies:

flutter pub add --dev cbl_generator:0.4.0-dev.6 build_runner

Create typed data classes and annotated them with TypedDocument and TypedDictionary:

// user.dart

import 'package:cbl/cbl.dart';

// Declare the part file into which the generated code will be written.
part 'user.cbl.type.g.dart';

// Per default the type of a document is encoded in the `type` property in
// the underlying data. The value is a string that is the name of the annotated
// class. This can be customized by setting `TypedDocument.typeMatcher`.
@TypedDocument()
abstract class User with _$User {
  factory User({
    @DocumentId() String? id,
    required PersonalName name,
    String? email,
    required String username,
    required DateTime createdAt,
  }) = MutableUser;
}

@TypedDictionary()
abstract class PersonalName with _$PersonalName {
  factory PersonalName({
    required String first,
    required String last,
  }) = MutablePersonalName;
}

Create a typed database by annotating a class with TypedDatabase:

// app_database.dart

import 'package:cbl/cbl.dart';

import 'user.dart';

@TypedDatabase(
  // List all the typed data classes that will be used in the database.
  types: {
    User,
    PersonalName,
  },
)
abstract class $AppDatabase {}

Run the build runner to invoke the generator:

dart run build_runner build
# or
flutter run build_runner build

Open an instance of the typed database and use it:

import 'app_database.cbl.database.g.dart';
import 'user.dart';

Future<void> useTypedDatabase() {
  // Use a static method on the generated typed database class to open an instance.
  final db = await AppDatabase.openAsync('app');

  // Every typed data class has a mutable and immutable variant. The mutable
  // class has the same name as the immutable class, but with the `Mutable`
  // suffix. A mutable instance can be created by constructing it, or from
  // an immutable instance, through the `toMutable` method.
  final user = MutableUser(
    name: PersonalName(first: 'Alice', last: 'Green'),
    email: 'alice@green.com',
    username: 'ali',
    createdAt: DateTime.now(),
  );

  // The API to save typed documents is slightly different than the API to
  // save plain documents. `saveTypedDocument` returns an object that has methods
  // for saving the document with conflict resolution through concurrency control or
  // a custom conflict handler.
  await database.saveTypedDocument(user).withConcurrencyControl();

  // To retrieve a typed document, use the `typedDocument` method and pass it the
  // type of the requested document through the type parameter.
  final savedUser = await database.typedDocument<User>(user.id);
}

Getting started​

Getting started