public static IEnumerable <IEventMessage <DomainAggregateEvent> > Upgrade <TSource>(
this IEventMessage <TSource> oldMessage, params DomainAggregateEvent[] newEvents)
where TSource : DomainAggregateEvent
{
return(newEvents.Select(newEvent =>
(IEventMessage <DomainAggregateEvent>)UpgradedEventMessage.Create(oldMessage, newEvent)));
}
public static IEnumerable <IEventMessage <DomainAggregateEvent> > Replace <TSource>(
this IEnumerable <IEventMessage <DomainAggregateEvent> > eventStream,
Func <IEventMessage <TSource>, IEnumerable <DomainAggregateEvent> > upgradeFunction)
where TSource : DomainAggregateEvent
{
foreach (var message in eventStream)
{
if (message.Event is TSource)
{
var newEvents = upgradeFunction(message as IEventMessage <TSource>);
foreach (var newEvent in newEvents)
{
yield return((IEventMessage <DomainAggregateEvent>)UpgradedEventMessage.Create(message, newEvent));
}
}
yield return(message);
}
}
public IEnumerable <IEventMessage <DomainAggregateEvent> > UpgradeSequenceNumbers(
IEnumerable <IEventMessage <DomainAggregateEvent> > eventStream)
{
int sequenceNumber = 1;
foreach (var message in eventStream)
{
long messageNumber = sequenceNumber;
long?originalSequenceNumber = message.Metadata.GetStreamSequenceNumber();
UpgradedEventMessage upgradedMessage = message as UpgradedEventMessage;
if (originalSequenceNumber != messageNumber)
{
upgradedMessage ??= UpgradedEventMessage.Create(message, message.Event);
upgradedMessage.MetadataOverrides[BasicEventMetadataNames.StreamSequenceNumber] = () => messageNumber.ToString();
}
if (upgradedMessage != null)
{
if (!upgradedMessage.Metadata.ContainsKey(BasicEventMetadataNames.AggregateVersion) &&
originalSequenceNumber != null)
{
upgradedMessage.MetadataOverrides[BasicEventMetadataNames.AggregateVersion] = () => originalSequenceNumber.ToString();
}
yield return((IEventMessage <DomainAggregateEvent>)upgradedMessage);
}
else
{
yield return(message);
}
sequenceNumber++;
}
}