Create AtCollection from Dart primitive

Learn how to create an AtCollection object that holds Dart primitives

Use dart primitives when you want to create a collection that is based on Dart primitives.

This is Path B from the Introduction. Use this when you just want to store a Map, String, Uint8List, or other type that Dart's jsonEncode already handles.

Unlike what is done in Create AtCollection from domain object, you do not need fromJson or typeTag. The SDK knows how to serialize and deserialize these natively.

Examples

Maps

final AtCollection<Map> maps = await atClient.collection<Map>(
  'maps.my_app',
  const Duration(days: 7),
);

Strings

final AtCollection<String> strings = await atClient.collection<String>(
  'strings.my_app',
  const Duration(days: 7),
);

await strings.create(
  obj: 'this is just a String',
  sharedWith: otherAtSigns,
);

Lists

final AtCollection<List<String>> tags = await atClient.collection<List<String>>(
  'tags.my_app',
  const Duration(days: 7),
);

Binary data (Uint8List)

import 'dart:typed_data';

final AtCollection<Uint8List> binaries = await atClient.collection<Uint8List>(
  'binary.my_app',
  const Duration(days: 7),
);

Untyped (generic) collections

You can create a collection with no type parameter. This gives you an AtCollection<dynamic> that accepts any Dart primitive in the same collection. No fromJson, typeTag, or registerFactory call is needed - the SDK tags every primitive as 'n/a' internally and round-trips them through jsonDecode automatically.

final AtCollection generic = await atClient.collection(
  'mixed.my_app',
  const Duration(days: 7),
);

await generic.create(
  obj: {'key': 'value', 'count': 42},
  sharedWith: otherAtSigns,
);
await generic.create(obj: 'just a string', sharedWith: otherAtSigns);
await generic.create(obj: ['dart', 'flutter'], sharedWith: otherAtSigns);
await generic.create(obj: 42, sharedWith: otherAtSigns);
await generic.create(obj: true, sharedWith: otherAtSigns);

for (final CItem item in await generic.getItems()) {
  print('${item.obj.runtimeType}: ${item.obj}');
}

You lose compile-time type safety on item.obj (it is dynamic), so cast when you read back:

for (final CItem item in await generic.getItems()) {
  if (item.obj is Map) {
    final Map map = item.obj as Map;
    print('map with ${map.length} entries');
  } else if (item.obj is String) {
    print('string: ${item.obj}');
  }
}

You are ready to move onto AtCollection.create.