/// <summary>
/// Gets an <see cref="IInvoice"/>.
/// </summary>
/// <param name="key">
/// The key.
/// </param>
/// <returns>
/// The <see cref="IInvoice"/>.
/// </returns>
protected override IInvoice PerformGet(Guid key)
{
var sql = GetBaseQuery(false)
.Where(GetBaseWhereClause(), new { Key = key });
var dto = Database.Fetch<InvoiceDto, InvoiceIndexDto, InvoiceStatusDto>(sql).FirstOrDefault();
if (dto == null)
return null;
var lineItems = GetLineItemCollection(key);
var orders = GetOrderCollection(key);
var factory = new InvoiceFactory(lineItems, orders);
return factory.BuildEntity(dto);
}