OneOffTask
- Flutter course
- Advanced
- Lesson 43/69
- 4 min
Schedule one-off tasks with OneOffTask.
What is OneOffTask?
OneOffTask represents a background task that runs once. It is registered with Workmanager().registerOneOffTask; the task runs once after a while. The first parameter is the task id and the second is the name passed to callbackDispatcher.
Workmanager().registerOneOffTask(
'sync-task',
'sync',
);registerOneOffTask
The registerOneOffTask method schedules a one-time task. You tag the task with tag and provide a start delay with initialDelay. When the task runs, callbackDispatcher is called and the name in the second parameter arrives as task.
Workmanager().registerOneOffTask(
'sync-task',
'sync',
initialDelay: Duration(seconds: 10),
);Practice Register a one-off task
Register a task with Workmanager().registerOneOffTask using id 'sync-task' and callback name 'sync', and print 'ok'.
Starter code
class Workmanager {
void initialize(Function dispatcher, {bool isInDebugMode = false}) {}
void registerOneOffTask(String uniqueId, String taskName, {Duration? initialDelay}) {}
}
bool callbackDispatcher(String task) => true;
void main() {
// tek seferlik görev kaydet
// 'ok' yazdır
}Sample solution
class Workmanager {
void initialize(Function dispatcher, {bool isInDebugMode = false}) {}
void registerOneOffTask(String uniqueId, String taskName, {Duration? initialDelay}) {}
}
bool callbackDispatcher(String task) => true;
void main() {
Workmanager().registerOneOffTask('sync-task', 'sync');
print('ok');
}Expected output
ok
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 How many times does OneOffTask run?
- Continuously, at fixed intervals
- Only once Correct answer
- On every app launch
- Never runs
Explanation: OneOffTask runs only once; for periodic execution you use PeriodicTask.
2 Register a one-off task
Workmanager().____(
'sync-task',
'sync',
);Workmanager().registerOneOffTask(
'sync-task',
'sync',
);Explanation: To register a one-off task you call the registerOneOffTask method; the first parameter is the task id.
3 OneOffTask parts
| Term | Meaning |
|---|---|
registerOneOffTask |
One-off registration |
'sync-task' |
Task identifier |
'sync' |
Callback name |
initialDelay |
Initial delay |