/// <summary>
/// Checks that if the given aggregate root has been updated in the event store by another process.
/// </summary>
/// <param name="aggregateRoot">The aggregate root.</param>
/// <returns></returns>
/// <exception cref="AggregateConcurrencyException"></exception>
protected async Task ConcurrencyCheck(TAggregateRoot aggregateRoot)
{
IDocumentQuery <TEventSet> eventQuery = Client
.CreateDocumentQuery <TEventSet>(_databaseCollectionUri)
.Where(eventSet => eventSet.AggregateId == aggregateRoot.Id)
.AsDocumentQuery();
FeedResponse <TEventSet> result = await eventQuery.ExecuteNextAsync <TEventSet>();
int persistedVersion = result.Max(eventSet => (int?)eventSet.AggregateVersion) ?? 0;
if (aggregateRoot.Version != persistedVersion + 1)
{
string errorMessage =
$"The aggregate with aggregate root of type {aggregateRoot.GetType().Name} has been modified and the event stream cannot be appended.";
throw new AggregateConcurrencyException(errorMessage);
}
}
