public IHttpActionResult Post(Product product)
 {
     if (!ModelState.IsValid)
     {
         return BadRequest(ModelState);
     }
     db.Products.Add(product);
     //db.SaveChanges();
     return Created(product);
 }
        // PUT: odata/Products(5)
        public IHttpActionResult Put([FromODataUri] int key, Product product)
        {
            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }

            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }

            if (key != product.ProductID)
            {
                return BadRequest();
            }

            db.Products.Attach(product);
            db.Entry(product).State = EntityState.Modified;

            try
            {
                db.SaveChanges();
            }
            catch (DbUpdateConcurrencyException)
            {
                if (!ProductExists(key))
                {
                    return NotFound();
                }
                else
                {
                    throw;
                }
            }

            return Updated(product);
        }