How to get Bitcoin value for corresponding COP value in ASP.NET C#?

Question

I want to get Bitcoin value for corresponding cop value and store it in table or variable. I got this URL from which I can get a Bitcoin value for usd amount. I searched on bitpay and I found this URL.

For example:

100.000 cop = 0,0248 btc

https://bitpay.com/rates/COP

https://bitpay.com/downloads/bitpayApi.pdf

https://bitpay.com/api#resource-Rates

I tried:

var uri=

String.Format("https://bitpay.com/rates/COP",Convert.ToDecimal(textBox1.Text ));

   WebClient client = new WebClient();
        client.UseDefaultCredentials = true;
        var data = client.DownloadString(uri);

        var result = Convert.ToDouble(data);

        textBox3.Text = data;

at the end, its COP value which we want to convert in Bitcoin. I want to get the result in the variable in C# (backend).

How can I accomplish this?

Answer 1

First, you need to understand how the API responds to you. It responds with JSON that is always prefixed with data: {}. You can use Newtonsoft.Json and the JObject.Parse() method to find the data token and select its properties. You can then deserialize that with Newtonsoft.Json into a class that models the rates. A rate has code, name, and rate properties.

Let's declare our class:

public class RateModel {
    public string Code { get; set; }

    public string Name { get; set; }

    public decimal Rate { get; set; }
}

Now we need to call the API correctly to get a response. I did so in a little console app as follows:

private static void Main(string[] args) {
    try {
        string cryptoCurrencyCode = "BTC";
        string countryCurrencyCode = "COP";
        string uri = string.Format("https://bitpay.com/rates/{0}/{1}", cryptoCurrencyCode, countryCurrencyCode);

        var client = new WebClient();
        client.UseDefaultCredentials = true;

        //Everything is returned inside of a "data" property, so let's select that token.
        string data = JObject.Parse(client.DownloadString(uri)).SelectToken("data").ToString();
        var rate = JsonConvert.DeserializeObject<RateModel>(data);

        Console.WriteLine("1 {0} = {1} {2}", cryptoCurrencyCode, rate.Rate, countryCurrencyCode);
    } catch (Exception ex) {
        Console.WriteLine("Caught exception: {0}", ex.ToString());
    } finally {
        Console.WriteLine("Press Enter to exit.");
        Console.ReadLine();
    }
}

And of course, if all we care about is the rate and we do not care about presenting any of the other data such as name or code, then we could omit creating a class to house the other data and simply select that token itself:

        var json = JObject.Parse(client.DownloadString(uri));
        decimal rate = 0;
        bool parsed = Decimal.TryParse(json.SelectToken("data").SelectToken("rate").ToString(), out rate);

        if(!parsed) {
            Console.WriteLine("Failed to parse the rate.");
        } else {
            Console.WriteLine("1 {0} = {1} {2}", cryptoCurrencyCode, rate, countryCurrencyCode);
        }