/// <summary>
/// Finds or creates a new aggregate if it doesn't exist, runs the update handler and saves it.
/// </summary>
/// <typeparam name="T">Type of the aggregate</typeparam>
/// <param name="repository">repository instance</param>
/// <param name="id">the aggregate id</param>
/// <param name="handler">the create/update handler</param>
/// <returns>A Task containing the created or updated aggregate</returns>
public static async Task <T> CreateOrUpdate <T>(this IAggregateRepository <T> repository, string id, Action <T> handler)
where T : IAggregate
{
var aggregate = await repository.FindOrDefault(id);
handler(aggregate);
await repository.Save(aggregate);
return(aggregate);
}
