public async Task<IHttpActionResult> Put(int key, Customer customer, ODataQueryOptions<Customer> options)
{
if (!ModelState.IsValid)
{
return BadRequest(ModelState);
}
if (!(key == customer.Id))
{
return BadRequest("The customer Id must match the key in the URI");
}
if (options.IfMatch != null)
{
if (!_context.Customers.Where(c => c.Id == key).Any())
{
// The entity doesn't exist on the database and as the request contains an If-Match header we don't
// insert the entity instead (No UPSERT behavior if the If-Match header is present).
return NotFound();
}
else if (!((IQueryable<Customer>)options.IfMatch.ApplyTo(_context.Customers.Where(c => c.Id == key))).Any())
{
// The ETag of the entity doesn't match the value sent on the If-Match header, so the entity has
// been modified by a third party between the entity retrieval and update..
return StatusCode(HttpStatusCode.PreconditionFailed);
}
else
{
// The entity exists in the database and the ETag of the entity matches the value on the If-Match
// header, so we update the entity.
_context.Entry(customer).State = EntityState.Modified;
await _context.SaveChangesAsync();
return Ok(customer);
}
}
else
{
if (!_context.Customers.Where(c => c.Id == key).Any())
{
// The request didn't contain any If-Match header and the entity doesn't exist on the database, so
// we create a new one. For more details see the section 11.4.4 of the OData v4.0 specification.
_context.Customers.Add(customer);
await _context.SaveChangesAsync();
return base.Created(customer);
}
else
{
// the request didn't contain any If-Match header and the entity exists on the database, so we
// update it's value.
_context.Entry(customer).State = EntityState.Modified;
await _context.SaveChangesAsync();
return Ok(customer);
}
}
}
private static void RunQueries()
{
HttpClient client = new HttpClient();
HttpRequestMessage request;
HttpResponseMessage response;
// Retrieving an entity for the first time. Observe that the ETag is in the response headers and
// the returned payload contains the annotation @odata.etag indicating the ETag associated with that customer.
Console.WriteLine("Retrieving a single customer at {0}/odata/Customers(1)", serverUrl);
Console.WriteLine();
request = new HttpRequestMessage(HttpMethod.Get, serverUrl + "/odata/Customers(1)");
response = client.SendAsync(request).Result;
response.EnsureSuccessStatusCode();
Console.WriteLine(response.ToString());
dynamic customer = JObject.Parse(response.Content.ReadAsStringAsync().Result);
Console.WriteLine(customer);
Console.WriteLine();
Console.WriteLine("-----------------------------------------------------");
string etag = customer["@odata.etag"];
// Retrieving the same customer as in the previous request but only if the ETag doesn't match the one
// specified in the If-None-Match header. We are sending the ETag value that we obtained from the previous
// request, so we expect to see a 304 (Not Modified) response.
Console.WriteLine("Retrieving the customer at {0}/odata/Customers(1) when the Etag value sent matches");
request = new HttpRequestMessage(HttpMethod.Get, serverUrl + "/odata/Customers(1)");
request.Headers.IfNoneMatch.Add(EntityTagHeaderValue.Parse(etag));
response = client.SendAsync(request).Result;
Console.WriteLine("The response status code is: {0}", response.StatusCode);
Console.WriteLine();
Console.WriteLine("-----------------------------------------------------");
// Retrieving the same customer as in the previous request but only if the ETag doesn't match the one
// specified in the If-None-Match header. We are sending a different ETag value, so we expect to see a 200
// (OK) response.
Console.WriteLine("Retrieving the customer at {0}/odata/Customers(1) when the Etag value sent matches");
request = new HttpRequestMessage(HttpMethod.Get, serverUrl + "/odata/Customers(1)");
request.Headers.IfNoneMatch.Add(EntityTagHeaderValue.Parse("W/\"MQ==\""));
response = client.SendAsync(request).Result;
Console.WriteLine("The response status code is {0}", response.StatusCode);
Console.WriteLine(JObject.Parse(response.Content.ReadAsStringAsync().Result));
Console.WriteLine();
Console.WriteLine("-----------------------------------------------------");
// Removing the annotations from the customer object as they are not required on the following requests and
// changing the age value.
customer.Age = 99;
customer.Remove("@odata.etag");
customer.Remove("@odata.context");
// Trying to update the customer using a different ETag value than the ETag on the previous request. The
// server will return a 412 (Precondition Failed) response.
request = new HttpRequestMessage(HttpMethod.Put, serverUrl + "/odata/Customers(1)");
// Setting up a different ETag value.
request.Headers.IfMatch.Add(EntityTagHeaderValue.Parse("W/\"MQ==\""));
request.Content = new ObjectContent<JObject>(customer, new JsonMediaTypeFormatter());
Console.WriteLine("Trying to update the Customer using a different ETag value on the If-Match header and failing");
response = client.SendAsync(request).Result;
Console.WriteLine("The response status code is {0}", response.StatusCode);
Console.WriteLine();
Console.WriteLine("-----------------------------------------------------");
// Trying to update the customer using the ETag value retrieved from the first request. The server will
// process the request and return a 200 (OK) response.
request = new HttpRequestMessage(HttpMethod.Put, serverUrl + "/odata/Customers(1)");
request.Headers.IfMatch.Add(EntityTagHeaderValue.Parse(etag));
request.Content = new ObjectContent<JObject>(customer, new JsonMediaTypeFormatter());
Console.WriteLine("Trying to update a Customer using the same ETag value on the If-Match header and succeeding");
Console.WriteLine();
response = client.SendAsync(request).Result;
Console.Write(JObject.Parse(response.Content.ReadAsStringAsync().Result));
Console.WriteLine();
Console.WriteLine("-----------------------------------------------------");
// Trying to update the customer using the If-Match header and sending an entity that doesn't exist on the
// database. The behavior in this case is "strict update", meaning that the server shouldn't try to insert
// the entity instead, so the answer we receive is 404 (Not Found).
request = new HttpRequestMessage(HttpMethod.Put, serverUrl + "/odata/Customers(30)");
request.Headers.IfMatch.Add(EntityTagHeaderValue.Parse("W/\"MQ==\""));
Customer newCustomer = new Customer
{
Id = 30,
Name = "New customer",
Age = 30,
Version = 0
};
request.Content = new ObjectContent<Customer>(newCustomer, new JsonMediaTypeFormatter());
Console.WriteLine("Trying to update a non existing customer with the If-Match header present");
Console.WriteLine();
response = client.SendAsync(request).Result;
Console.WriteLine("The response status code is {0}", response.StatusCode);
Console.WriteLine();
Console.WriteLine("-----------------------------------------------------");
// Trying the same request but without the If-Match header. The behavior in this case is "update or insert",
// meaning that the server should try to insert the entity if it doesn't exist, so the answer we receive is
// 201 (Created).
request = new HttpRequestMessage(HttpMethod.Put, serverUrl + "/odata/Customers(30)");
request.Content = new ObjectContent<Customer>(newCustomer, new JsonMediaTypeFormatter());
Console.WriteLine("Trying to update a non existing customer without the If-Match header");
Console.WriteLine();
response = client.SendAsync(request).Result;
Console.WriteLine("The response status code is {0}", response.StatusCode);
Console.WriteLine(JObject.Parse(response.Content.ReadAsStringAsync().Result));
Console.WriteLine();
Console.WriteLine("-----------------------------------------------------");
}
