Summary - Hive
- Flutter course
- Advanced
- Lesson 15/69
- 4 min
Combine Box, put and TypeAdapter to make a settings store.
Settings store
When building a settings store, you combine box, put and TypeAdapter. First you register an adapter for the Settings class, then open a box and store the settings object. When the app reopens, you read from the box to restore the settings.
Hive.registerAdapter(SettingsAdapter());
final box = await Hive.openBox('app_settings');
await box.put('current', Settings('light'));Practice Build a settings store
Define a Settings class (final String theme). Write a SettingsAdapter with typeId 1 and read/write methods. Register the adapter, initialize Hive, open a box named 'app_settings', put Settings('light') under key 'current', retrieve it and print the theme.
Starter code
import 'package:hive/hive.dart';
// Settings sınıfı: final String theme
// SettingsAdapter: typeId = 1
// read ve write metodları
void main() async {
// adapter kaydet
// Hive'ı başlat
// 'app_settings' box'ını aç
// 'current' anahtarına Settings('light') koy
// değeri al ve theme'i yazdır
}Sample solution
import 'package:hive/hive.dart';
class Settings {
final String theme;
Settings(this.theme);
}
class SettingsAdapter extends TypeAdapter<Settings> {
@override
final int typeId = 1;
@override
Settings read(BinaryReader reader) {
return Settings(reader.readString());
}
@override
void write(BinaryWriter writer, Settings obj) {
writer.writeString(obj.theme);
}
}
void main() async {
Hive.registerAdapter(SettingsAdapter());
Hive.init('hive_data');
final box = await Hive.openBox('app_settings');
await box.put('current', Settings('light'));
final settings = box.get('current') as Settings;
print(settings.theme);
await box.close();
}Expected output
light
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 When should a TypeAdapter be registered?
- Only on error
- Before opening a box that contains the custom type Correct answer
- After the box is closed
- At the end of the main function
Explanation: The adapter must be registered before opening a box that uses the type; otherwise Hive does not recognize the type.
2 Adapter read method
Settings read(BinaryReader reader) {
return Settings(reader.____());
}Settings read(BinaryReader reader) {
return Settings(reader.readString());
}Explanation: The readString method of BinaryReader reads string values; it is used in the adapter's read method.
3 Settings store parts
| Term | Meaning |
|---|---|
Settings |
Settings model |
SettingsAdapter |
Type converter |
'app_settings' |
Box name |
settings.theme |
Stored value |