public static bool SetNewPrice(string name, decimal price, string comment, string sellingPointTitle)
        {
            if (name == null)
            {
                throw new ArgumentNullException(nameof(name));
            }
            if (comment == null)
            {
                throw new ArgumentNullException(nameof(comment));
            }
            if (sellingPointTitle == null)
            {
                throw new ArgumentNullException(nameof(sellingPointTitle));
            }
            if (price <= 0)
            {
                throw new ArgumentOutOfRangeException(nameof(price));
            }

            using (var sb = new ShawarmaBaseEntities())
            {
                Shawarma shawarma = sb.Shawarma.FirstOrDefault(sh => sh.ShawarmaName == name);
                if (shawarma == null)
                {
                    return(false);
                }

                SellingPoint sp = sb.SellingPoint.FirstOrDefault(s => s.ShawarmaTitle == sellingPointTitle);
                if (sp == null)
                {
                    return(false);
                }

                PriceController pc = sb.PriceController.FirstOrDefault(p => p.ShawarmaId == shawarma.ShawarmaId && p.SellingPointId == sp.SellingPointId);
                if (pc == null)
                {
                    pc = new PriceController
                    {
                        Price          = price,
                        Comment        = comment,
                        SellingPointId = sp.SellingPointId,
                        ShawarmaId     = shawarma.ShawarmaId
                    };
                    sb.PriceController.Add(pc);
                }
                else
                {
                    pc.Price   = price;
                    pc.Comment = comment;
                }

                return(SaveIt(sb));
            }
        }
        public static bool AddSellingPoint(string title, string address, string category)
        {
            using (var sb = new ShawarmaBaseEntities())
            {
                var pointCat = sb.SellingPointCategory.FirstOrDefault(selling => selling.SellingPointCategoryName == category);
                if (pointCat == null)
                {
                    return(false);
                }

                SellingPoint point = new SellingPoint
                {
                    ShawarmaTitle          = title,
                    Address                = address,
                    SellingPointCategoryId = pointCat.SellingPointCategoryId
                };

                sb.SellingPoint.Add(point);
                return(SaveIt(sb));
            }
        }