axon 4 snapshot in demand - spring-boot

Question

I work with spring boot and axon example, i implement the snapshot feature, with the below code is working fine, after 3 events i found the data in the table snapshot_event_entry in the database
#Configuration
#AutoConfigureAfter(value = { AxonAutoConfiguration.class })
public class AxonConfig {
#Bean
public SnapshotTriggerDefinition catalogSnapshotTrigger(Snapshotter snapshotter) {
return new EventCountSnapshotTriggerDefinition(snapshotter, 3);
}
}
#Aggregate(snapshotTriggerDefinition = "catalogSnapshotTrigger")
public class CatalogAggregate { }
My question, is there a method to do a snapshot in demand? That means i want to implement an api to do the snapshot, not automatically after 3 events

Answer 1

there is nothing already in place.
One way to implement what you need is to create a dedicated Command, eg PerformShapshotCmd, that will carry the aggregateId information, and a #CommandHandler into your Aggregate. You could then let Spring autowire the Snapshotter instance bean, and call for the scheduleSnapshot(Class<?> aggregateType, String aggregateIdentifier) method.
Below some code snippet that could guide you.
data class PerformShapshotCmd(#TargetAggregateIdentifier val id: String)
#CommandHandler
public void handle(PerformShapshotCmd cmd, Snapshotter snapshotter) {
logger.debug("handling {}", cmd);
snapshotter.scheduleSnapshot(this.getClass(), cmd.getId());
}
You should also define one Bean of type Snapshotter into your config
#Bean
public SpringAggregateSnapshotterFactoryBean snapshotter() {
SpringAggregateSnapshotterFactoryBean springAggregateSnapshotterFactoryBean = new SpringAggregateSnapshotterFactoryBean();
//Setting async executors
springAggregateSnapshotterFactoryBean.setExecutor(Executors.newSingleThreadExecutor());
return springAggregateSnapshotterFactoryBean;
}
Please note that the first argument of your commandHandler needs to be the command, otherwise the framework will complain with an exception at startup time.