Regarding mvc4 web api - asp.net-mvc

Question

HEllo this is some piece of mvc4 webapi code can anyone over here explain me each line of code..I googled but didnt find any thing interesting
public HttpResponseMessage PostProduct(Product item)
{
item = repository.Add(item);
var response = Request.CreateResponse(HttpStatusCode.Created, item);
string uri = Url.RouteUrl("DefaultApi", new { id = item.Id });
response.Headers.Location = new Uri(uri);
return response;
}
I only understand that I am sending product item..and in return this web api returns me response of newly added product but I didnt understand this 2 lines in particular
string uri = Url.RouteUrl("DefaultApi", new { id = item.Id });
response.Headers.Location = new Uri(uri);

Answer 1

public HttpResponseMessage PostProduct(Product item)
{
//creates and adds an item to repository(db)
item = repository.Add(item);
//creates a new httpresponse
var response = Request.CreateResponse(HttpStatusCode.Created, item);
//creates new uri
string uri = Url.RouteUrl("DefaultApi", new { id = item.Id });
//set header for new uri
response.Headers.Location = new Uri(uri);
return response;
}
This lines will create a new RouteUrl -> basically a link for your response header.
My advice would be that you should start with official documentation from here: http://www.asp.net/web-api , it worked for me. There are many things to be researched here: http://geekswithblogs.net/JoshReuben/archive/2012/10/28/aspnet-webapi-rest-guidance.aspx
There are too many examples to be posted in this answer, that may help you.
· Response code: By default, the Web API framework sets the response
status code to 200 (OK). But according to the HTTP/1.1 protocol, when
a POST request results in the creation of a resource, the server
should reply with status 201 (Created). Non Get methods should return
HttpResponseMessage
· Location: When the server creates a resource, it should include the
URI of the new resource in the Location header of the response.
public HttpResponseMessage PostProduct(Product item)
{
item = repository.Add(item);
var response = Request.CreateResponse<Product>(HttpStatusCode.Created, item);
string uri = Url.Link("DefaultApi", new { id = item.Id });
response.Headers.Location = new Uri(uri);
return response;
}

Answer 2

public HttpResponseMessage PostProduct(Product item)
//this means that any post request to this controller will hit this action method
{
item = repository.Add(item);
//the posted data would be added to the already defined repository
var response = Request.CreateResponse(HttpStatusCode.Created, item);
//a responses is created with code 201. which means a new resource was created.
string uri = Url.RouteUrl("DefaultApi", new { id = item.Id });
//you get a new url which points to the route names DefaultAPI and provides a url parameter id(normally defined as optional)
response.Headers.Location = new Uri(uri);
//adds the created url to the headers to the response
return response;
//returns the response
}
normally as the standards go a POST request is used to create an entity. and the data to be put in that entity is sent with the request.
so the code here is creating the entity and then in the response sending back the url on which you can find the recently created entity. this is what any client would expect who is following the standards. Though this aint at all necessary.
so according to this you must have a GET action method that accepts the id as an parameter and returns the product corresponding to that id