ASP.NET Web APi - Passing an object as parameter

Question

MakeUser method in the User controller for creating a username and password.

[HttpGet]
public string MakeUser(UserParameters p)
{
 const string chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
 string pass = "";
 Random r = new Random();
 for (int i = 0; i < p.Number; i++)
 {
 pass += chars[r.Next(0, 62)];
 }
 string firstTwoo = p.Name.Substring(0, 2);
 string firstThree = p.Surname.Substring(0, 3);
 return "Your username is: " + firstTwoo + firstThree + "\nYour password is: " + pass;
}

UserParameter class for sending the parameters as an object.

public class UserParameters
{
 public int Number { get; set; }
 public string Name { get; set; }
 public string Surname { get; set; } 
}

RunAsync method in console client. Can i pass an object with Get method? If yes what is my mistake here? Thank you!

static async Task RunAsync()
{
 using (var client = new HttpClient())
 {
 var p = new UserParameters();
 Console.Write("Your username: ");
 p.Name = Console.ReadLine();
 Console.Write("Your surname: ");
 p.Surname = Console.ReadLine();
 Console.Write("Please type a number between 5 and 10: ");
 p.Number = int.Parse(Console.ReadLine());
 client.BaseAddress = new Uri("http://localhost:4688/");
 client.DefaultRequestHeaders.Accept.Clear();
 client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
 //HTTP GET
 HttpResponseMessage response = await client.GetAsync("api/user?p=" + p);
 if (response.IsSuccessStatusCode)
 {
 var result = await response.Content.ReadAsAsync<UserParameters>();
 Console.WriteLine("\n*****************************\n\n" + result);
 }
 }
}

• Luiso: you cannot pass an object in a GET method, as model binding is not supported, at least not by default

Answer 1

GET requests don't support you passing objects in this way. The only option is to do it as a query string param as others have already demonstrated. From a design perspective, since you are creating a new resource it makes much more sense for this to be a POST or PUT request which both allow for an actual payload to be sent along with the request.

[HttpPost]
public string MakeUser([FromBody]UserParameters p)
{
 ...
}
var client = new HttpClient();
client.DefaultRequestHeaders.Accept.Clear();
var response = await client.PostAsJsonAsync(new Uri("http://localhost:4688/"), p);
// do something with response

• Attila Alan: Thanx Jesse, and how can i put the result in Console.WriteLine? Because i can do with Post method but i can not show the result.
• Jesse Carter: You should be able to do it exactly the same as with the GET. Nothing about Console changes just because its a POST instead of GET.
• Attila Alan: It gives error -response {StatusCode: 405, ReasonPhrase: 'Method Not Allowed', Version: 1.1, Content: System.Net.Http.StreamContent, Headers: { X-SourceFiles: =?UTF-8?B?RDpcQnVyZWF1YmxhZFxIZXJoYWxpbmdzb2VmZW5pbmdlbjJXZWJBUElcSGVyaGFsaW5nc29lZmVuaW5nZW4yV2ViQVBJ?= Cache-Control: private Date: 2016年1月15日 20:52:58 GMT Server: Microsoft-IIS/10.0 X-Powered-By: ASP.NET Content-Length: 5412 Allow: GET Allow: HEAD Allow: OPTIONS Allow: TRACE Content-Type: text/html; charset=utf-8 }} System.Net.Http.HttpResponseMessage
• Attila Alan: Thanx Jesse. After i did shut down it works like a charm.
• Jesse Carter: @AttilaAlan No problem, feel free to upvote or mark as answer if you found this helpful

Answer 2

Your variable p cannot be passed as query string parameter like how you have it. To populate the url and query strings the way you prefer, you would have to write out the rest of the query string and access the object's properties while building the string up.

string queryString = "api/user?name="+p.Name+"&surname="+p.Surname+"&number="+p.Number;
HttpResponseMessage response = await client.GetAsync(queryString);

The MakeUser() method will need to look similar to something below:

[HttpGet]
public string MakeUser(string name, string surname, int number) 
{
}

I am not seeing however where you are calling the MakeUser() method. Perhaps in the query string parameter you need to make it 'api/makeuser?'.

• Attila Alan: Thanx Chad thats the answer
• Amit Sinha: What if object has many property. i.e. UserParameter is very big one. Querystring willbe very long.

Answer 3

You CAN pass the p parameter like you want to, it's perfectly fine, take a look at the FromUri paragraph here where an object is used as a parameter:

https://learn.microsoft.com/en-us/aspnet/web-api/overview/formats-and-model-binding/parameter-binding-in-aspnet-web-api

The method takes an object as a parameter, not the indivudual members. You call it by specifying the members though.