PeriodicTask
- Flutter course
- Advanced
- Lesson 44/69
- 4 min
Schedule periodic tasks with PeriodicTask.
What is PeriodicTask?
PeriodicTask represents a background task that repeats at fixed intervals. It is registered with Workmanager().registerPeriodicTask; the frequency parameter sets the repeat duration. The minimum interval varies by platform.
Workmanager().registerPeriodicTask(
'sync-task',
'sync',
frequency: Duration(minutes: 15),
);Constraints with constraints
You use Constraints to restrict when a PeriodicTask runs. For example, it can be set to run only when charging or when the network is connected. This saves battery and data.
Workmanager().registerPeriodicTask(
'sync-task',
'sync',
frequency: Duration(minutes: 15),
constraints: Constraints(
networkType: NetworkType.connected,
),
);Practice Register a periodic task
Register a task with Workmanager().registerPeriodicTask using id 'sync-task', callback name 'sync', and a 15 minute frequency, and print 'ok'.
Starter code
class Workmanager {
void initialize(Function dispatcher, {bool isInDebugMode = false}) {}
void registerPeriodicTask(String uniqueId, String taskName, {required Duration frequency}) {}
}
bool callbackDispatcher(String task) => true;
void main() {
// periyodik görev kaydet
// 'ok' yazdır
}Sample solution
class Workmanager {
void initialize(Function dispatcher, {bool isInDebugMode = false}) {}
void registerPeriodicTask(String uniqueId, String taskName, {required Duration frequency}) {}
}
bool callbackDispatcher(String task) => true;
void main() {
Workmanager().registerPeriodicTask(
'sync-task',
'sync',
frequency: Duration(minutes: 15),
);
print('ok');
}Expected output
ok
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 Which parameter specifies the repeat interval of PeriodicTask?
- frequency Correct answer
- tag
- constraints
- initialDelay
Explanation: The frequency parameter sets the repeat interval; initialDelay only sets the delay for the first run.
2 Register a periodic task
Workmanager().____(
'sync-task',
'sync',
frequency: Duration(minutes: 15),
);Workmanager().registerPeriodicTask(
'sync-task',
'sync',
frequency: Duration(minutes: 15),
);Explanation: To register a periodic task you call the registerPeriodicTask method; the frequency parameter sets the repeat interval.
3 PeriodicTask parts
| Term | Meaning |
|---|---|
registerPeriodicTask |
Periodic registration |
frequency |
Repeat interval |
Constraints |
Run constraints |
NetworkType.connected |
When network is connected |