public IEnumerable <PurchaseDTO> Purchases(int id, string filter)
{
CheckCredentials(id);
Func <PurchaseDTO, bool> test = filter.ToTest <PurchaseDTO>();
TEntity entity = FindEntity(id);
CollectCl(entity);
entity.CommercialLink.ForEach(cl => ClService.CollectPurchases(cl));
return(entity.CommercialLink.Reduce <CommercialLink, IEnumerable <PurchaseDTO> >(
(ret, cl) => ret.Concat(
cl.Purchase
.Select(purchase => PurchaseService.EntityToDTO(purchase))
.Where(test)
),
Enumerable.Empty <PurchaseDTO>()
));
}
