Models

Flutter Data models are data classes that extend DataModel and are annotated with @DataRepository:

@DataRepository([TaskAdapter])
@JsonSerializable()
class Task extends DataModel<Task> {
  @override
  final int? id;
  final String title;
  final bool completed;

  Task({this.id, required this.title, this.completed = false});
}

DataModel automatically registers new data classes within the framework and enforces the implementation of an id getter. Use the type that better suits you: int? and String? are the most common.

The json_serializable library is helpful but not required.

  • Model with @JsonSerializable? You don’t need to declare fromJson or toJson
  • Model without @JsonSerializable? You must declare fromJson and toJson

If you choose it, you can make use of @JsonKey and other configuration parameters as usual. A common use-case is having a different remote id attribute such as objectId. Annotating id with @JsonKey(name: 'objectId') takes care of it.

Freezed support

Here’s an example:

@freezed
@DataRepository([TaskAdapter])
class Task extends DataModel<Task> with _$Task {
  Task._();

  factory Task({
    int? id,
    required String name,
    required BelongsTo<User> user,
  }) = _Task;

  factory Task.fromJson(Map<String, dynamic> json) => _$TaskFromJson(json);
}

Unions haven’t been tested yet.

Omitting attributes

In order to omit an attribute simply use @JsonKey(ignore: true).

Extension methods

In addition, various useful methods become available on the class:

save

final user = User(id: 1, name: 'Frank');
await user.save();

The call is syntax-sugar for Repository#save and takes the same arguments (except the model).

Or, saving locally (i.e. remote: false) with a sync API:

final user = User(id: 1, name: 'Frank');
user.saveLocal();

delete

final user = await repository.findOne(1);
await user.delete();

It is syntax-sugar for Repository#delete and takes the same arguments (except the model).

Or, deleting locally (i.e. remote: false) with a sync API:

final user = User(id: 1, name: 'Frank');
user.deleteLocal();

find

final updatedUser = await user.find();

It’s syntax-sugar for Repository#findOne and takes the same arguments (except the model/ID).

Or, reloading locally (i.e. remote: false) with a sync API:

final user = User(id: 1, name: 'Frank');
final user2 = user.reloadLocal();

withKeyOf

Used whenever we need to transfer identity to a model without identity (that is, without an ID).

final user = User(id: 1, 'Parker');
final user2 = user.copyWith(name: 'Frank').withKeyOf(user);

id will still be null but saving and retreiving will work:

await user2.save(remote: false);
final user3 = await user2.find();
// user3.id == 1

Any Dart file that wants to use these extensions must import the library.

import 'package:flutter_data/flutter_data.dart';

VSCode protip! Type Command + . over the missing method and choose to import!

You can also disable them by hiding the extension:

import 'package:flutter_data/flutter_data.dart' hide DataModelExtension;

Polymorphic models

An example where Staff and Customer are both Users:

abstract class User<T extends User<T>> extends DataModel<T> {
  final String id;
  final String name;
  User({this.id, this.name});
}

@JsonSerializable()
@DataRepository([JSONAPIAdapter, BaseAdapter])
class Customer extends User<Customer> {
  final String abc;
  Customer({String id, String name, this.abc}) : super(id: id, name: name);
}

@JsonSerializable()
@DataRepository([JSONAPIAdapter, BaseAdapter])
class Staff extends User<Staff> {
  final String xyz;
  Staff({String id, String name, this.xyz}) : super(id: id, name: name);
}

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