如何从webapi控制器中的json反序列化参数

Question

seems like I have the most basic problem, yet I cannot find the documentation I need to solve it.

I have an mvc webapi controller:

public class TestController : ApiController
{
    [HttpGet]
    public MyClass Other([FromUri]MyClass id)
    {
        id.Value++;
        return id;
    }        
}

public class MyClass
{
    public int Value {get;set;}
}

which I am executing from a HttpClient:

using (var client = new System.Net.Http.HttpClient())
{
    client.BaseAddress = new System.Uri("http://localhost:31573/api/");
    client.DefaultRequestHeaders.Accept.Clear();
    client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
    var obj = new MyClass { Value = 3 };
    var data = JsonConvert.SerializeObject(obj);
    StringContent queryString = new StringContent(data, Encoding.UTF8, "application/json");
    var paramsValue = queryString.ReadAsStringAsync().Result;
    var response = client.GetAsync("Test/?id="+ paramsValue).Result;                    
    var textResponse = response.Content.ReadAsStringAsync().Result;
    var result = JsonConvert.DeserializeObject<MyClass>(textResponse);                    
 }

The problem is that the parameter id which is received by the controller is a default instance of MyClass (ie Value = 0). If I change the prototype of the method to accept a string:

[HttpGet]
public MyClass Other([FromUri]string id)
{
    var val = JsonConvert.DeserializeObject<MyClass>(id);
    val.Value++;
    return val; 
}    

it all works fine, but I would rather not have to manually do the deserialization in every controller method.

I have tried many combinations of how I create the query string, so far having no luck.

It appears that the data is getting to the webApi correctly, but the deserialization is not happening, so I suspect that I have not configure the webApi correctly to use json form the request parameters.

my webapiconfig looks like:

public static void Register(HttpConfiguration config)
        {
            if (config == null)
                throw new ArgumentNullException(nameof(config));

            // Web API configuration and services
            config.Formatters.Clear();
            config.Formatters.Add(new JsonMediaTypeFormatter());

            // Web API routes
            config.MapHttpAttributeRoutes();

            config.Routes.MapHttpRoute(
                name: "DefaultApi",
                routeTemplate: "api/{controller}/{id}",
                defaults: new { id = RouteParameter.Optional });
        }

so its returning json correctly, but incoming parameters are not deserialized correctly.

Can anyone help??

Answer 1

Thanks to the help from @Mostafizur Rahman, I came to the conclusion that a get method was not appropriate here, So I have changed to a Post method and pass the data in the body:

public class TestController : ApiController
{
    public MyClass PostMethod([FromBody]MyClass id)
    {            
        id.Value++;
        return id;
    }
}

public class MyClass
{
    public int Value {get;set;}
}

with the client side becoming:

using (var client = new System.Net.Http.HttpClient())
{
    client.BaseAddress = new System.Uri("http://localhost:31573/api/");
    client.DefaultRequestHeaders.Accept.Clear();
    client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
    var obj = new MyClass { Value = 3 };
    var data = JsonConvert.SerializeObject(obj);
    StringContent queryString = new StringContent(data, Encoding.UTF8, "application/json");
    var paramsValue = queryString.ReadAsStringAsync().Result;
    var response = client.PostAsync("Test/PostMethod",  queryString).Result;
    var textResponse = response.Content.ReadAsStringAsync().Result;
    var result = JsonConvert.DeserializeObject<MyClass>(textResponse);
}

Answer 2

this is the querystring that you'll need to form -

http://localhost:61817/api/Test?Value=3

Then the code changes like -

var response = client.GetAsync("Test?Value="+ obj.Value).Result;