/// <summary>
/// Retrieves existing aggregate from the store and executes the <see cref="aggregateTransformer"/> in
/// order to pass some command to the aggregate. As a result of <see cref="aggregateTransformer"/> execution
/// all changes of the aggregate will be persisted in the database.
/// </summary>
/// <param name="store"><see cref="IStore"/> instance which is used to transform the aggregate.</param>
/// <param name="aggregateId">Unique ID of an aggregate.</param>
/// <param name="aggregateTransformer">Generic transformer function that will be called if aggregate exists.</param>
/// <returns>Returns success if aggregate has been found and transformer executed without errors.</returns>
public static Task <Result> Borrow <T>(
this IStore store,
IAggregateId aggregateId,
Func <T, Result <T> > aggregateTransformer)
where T : AggregateRoot, new()
{
return(store.Borrow <T>(aggregateId, aggregate => Task.FromResult(aggregateTransformer(aggregate))));
}
/// <summary>
/// Borrow method with async aggregate transformer.
/// </summary>
public static Task <Result> Borrow <T>(
this IStore store,
IAggregateId aggregateId,
Func <T, Task <Result <T> > > aggregateTransformer)
where T : AggregateRoot, new() =>
store.Get <T>(aggregateId)
.OnSuccess(aggregateTransformer)
.OnSuccess(aggregate => store.SaveChanges(aggregate))
.OnFailure(
AggregateVersionMismatchError,
() => store.Borrow(aggregateId, aggregateTransformer));