public async Task<IHttpActionResult> PostCustomer(Customer customer)
        {
            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }

            customer.TrackingState = TrackingState.Added;
            _dbContext.ApplyChanges(customer);


            try
            {
                await _dbContext.SaveChangesAsync();
            }
            catch (DbUpdateException)
            {
                if (_dbContext.Customers.Any(c => c.CustomerId == customer.CustomerId))
                {
                    return Conflict();
                }
                throw;
            }

            await _dbContext.LoadRelatedEntitiesAsync(customer);
            customer.AcceptChanges();
            return CreatedAtRoute("DefaultApi", new { id = customer.CustomerId }, customer);
        }
        public async Task<IHttpActionResult> PutCustomer(Customer customer)
        {
            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }

            _dbContext.ApplyChanges(customer);

            try
            {
                await _dbContext.SaveChangesAsync();
            }
            catch (DbUpdateConcurrencyException)
            {
                if (!_dbContext.Customers.Any(c => c.CustomerId == customer.CustomerId))
                {
                    return Conflict();
                }
                throw;
            }

			await _dbContext.LoadRelatedEntitiesAsync(customer);
			customer.AcceptChanges();
	        return Ok(customer);
        }
 private static void EnsureTestCustomer(NorthwindDbContext context, string customerId, string territoryId)
 {
     var customer = context.Customers
         .SingleOrDefault(c => c.CustomerId == customerId);
     if (customer == null)
     {
         customer = new Customer
         {
             CustomerId = customerId, 
             CustomerName = "Test Customer " + customerId,
             TerritoryId = territoryId
         };
         context.Customers.Add(customer);
     }
 }
 public static void EnsureTestCustomer(string customerId, string customerName)
 {
     using (var context = CreateNorthwindDbContext(CreateNorthwindDbOptions))
     {
         var customer = context.Customers
             .SingleOrDefault(c => c.CustomerId == customerId);
         if (customer == null)
         {
             customer = new Customer
             {
                 CustomerId = customerId,
                 CustomerName = customerName
             };
             context.Customers.Add(customer);
             context.SaveChanges();
         }
     }
 }