public IHttpActionResult PostProduct(Product product)
 {
     if (ModelState.IsValid)
     {
         db.Products.Add(product);
         db.SaveChanges();
         var uri = new Uri(
             Url.Link(
                 "DefaultApi",
                 new { id = product.ID }));
         return Created(uri, product);
     }
     return BadRequest(ModelState);
 }
        public IHttpActionResult PutProduct(int id, Product product)
        {
            if (ModelState.IsValid && id == product.ID)
            {
                db.Entry(product).State = EntityState.Modified;
                try
                {
                    db.SaveChanges();
                }
                catch (DbUpdateConcurrencyException)
                {
                    return NotFound();
                }
                return Ok(product);
            }
            return BadRequest(ModelState);

        }