how to parse json data from a rest api using C# in the ASP.Net Core MVC model and display it on a HTML page

Question

I'm creating an ASP.Net core MVC application to retrieve and display current currencies with their values in a user friendly way on my html page. I am using cryptocompare's api to obtain these values.

The Json response I get from the api is

{"EUR":{"BTC":0.0003188,"USD":1.14}}

EUR.cs

namespace ProjectFinanceHub.Models
{

    public class EUR
    {
        public double BTC { get; set; }
        public double USD { get; set; }
    }

}

HomeController.cs Below I have removed my personal api key and replaced it 'your_api_here'

namespace ProjectFinanceHub.Controllers
{
    public class HomeController : Controller
    {
        public ActionResult Index()
        {
            return View();
        }

    public ActionResult About()
    {
        ViewBag.Message = "Your application description page.";

        return View();
    }

    public async Task<ActionResult> EUR()
    {
        var req = WebRequest.Create(@"https://min-api.cryptocompare.com/data/pricemulti?fsyms=EUR&tsyms=BTC,USD,EUR&api_key=your_api_here");
        var r = await req.GetResponseAsync().ConfigureAwait(false);

        var responseReader = new StreamReader(r.GetResponseStream());
        var responseData = await responseReader.ReadToEndAsync();

        var d = Newtonsoft.Json.JsonConvert.DeserializeObject<EUR>(responseData);
        return View(d);
     }
    }
 }

EUR.cshtml

@model ProjectFinanceHub.Models.EUR

<h2>@Model.BTC</h2> <!-- Should display 0.0003188 for example-->
<h3>@Model.USD</h3> <!-- Should display 1.13 for example-->

Currently I get values of 0 display for both BTC and USD, the expected values are that these values are the ones from the json response

Have you seen this SO answer? stackoverflow.com/questions/8157636/… — ste-fu
– ste-fu, Commented Jan 21, 2019 at 16:45
Possible duplicate of Can Json.NET serialize / deserialize to / from a stream? — TanvirArjel
– TanvirArjel, Commented Jan 21, 2019 at 16:51

Anu Viswan · Accepted Answer · 2019-01-21 17:37:22Z

4

You need to wrap EUR with a root element

public class EUR
{
    public double BTC { get; set; }
    public double USD { get; set; }
}

public class RootObject
{
    public EUR EUR { get; set; }
}

DeserializeObject object needs to be modified to

var d = Newtonsoft.Json.JsonConvert.DeserializeObject<RootObject>(responseData);

Please ensure your return d.EUR.

return View(d.EUR);

edited Jan 21, 2019 at 17:37

answered Jan 21, 2019 at 16:51

Anu Viswan

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2 Comments

ciara walsh Over a year ago

thank you for your response but I got this message when I loaded the page after making your changes. Server Error in '/' Application. The model item passed into the dictionary is of type 'ProjectFinanceHub.Models.RootObject', but this dictionary requires a model item of type 'ProjectFinanceHub.Models.EUR'. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Anu Viswan Over a year ago

You need return View(d. EUR)

John-Luke Laue · Accepted Answer · 2019-01-22 03:38:42Z

What fixed my problem was a mixed solution between implementing the changes @Anu pointed out and also thanks to https://stackoverflow.com/a/17788118/9864898 I reconfigured my controller as such

public async Task<ActionResult> EUR()
    {
        // output is {"EUR":{"BTC":0.0003188,"USD":1.13,"EUR":1}} for the below api at time of request
        var req = WebRequest.Create(@"https://min-api.cryptocompare.com/data/pricemulti?fsyms=EUR&tsyms=BTC,USD&api_key=your_api_key");
        var r = await req.GetResponseAsync().ConfigureAwait(false);

        var responseReader = new StreamReader(r.GetResponseStream());
        var responseData = new JsonTextReader(responseReader);

        var serializer = new JsonSerializer();

        var d = serializer.Deserialize<RootObject>(responseData);
        return View(d.EUR);
    }

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