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Posted 4 Jun 2012

Use C# to get JSON Data from the Web and Map it to .NET Class => Made Easy!

, 12 Feb 2014
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Easy steps on how to get JSON formatted data from a web service, deserialize it, and map it to custom local class for further usage


This tip/trick demonstrates a complete and easy solution on how to get JSON formatted data from a web service, and map (deserialize) it to custom .NET class for further usage.

Sample Data

As an example, we will use service which provides latest currency rates formatted as JSON data. Here is a sample of how that data looks like:  

  "disclaimer": "This data is collected from various providers ...",
  "license": "Data collected from various providers with public-facing APIs ...",
  "timestamp": 1336741253,
  "base": "USD",
  "rates": {
    "AED": 3.6731,
    "AFN": 48.419998,
    "ALL": 107.949997,
    "AMD": 393.410004,
    "ANG": 1.79,
    "AOA": 94.949997,
    // ... more values ...

So, how do we retrieve them through C# on the server side and use them? Read on to find out.

How To - Three Easy Steps

Step 1. Install Json.Net library

Json.NET library provides an easy, and de-facto, standard way to convert (serialize) .NET class to JSON data, and JSON data back to .NET class (deserialize). 

The easiest way to install Json.Net library into your .NET project is via NuGet Package Manager Console by running this command:

install-package Newtonsoft.Json 

Alternatively, if you need to install it manually, download it from its project page on CodePlex.

Step 2. Create .NET class which will match JSON data format

If you are using Visual Studio 2012+, you're in luck, since you can just paste a sample JSON data and it will create a class for you, To do that, first create a new class .cs file, select it in project explorer, than copy sample JSON data to clipboard, go to EDIT > Paste Special > Paste JSON as classes (thanks to Dave Kerr for this tip). More information on this feature here

If that won't work for you, or you'd prefer to do it yourself, you'll need to define .NET class manually. It must exactly match the format of JSON data provided by  

public class CurrencyRates {
  public string Disclaimer { get; set; }
  public string License { get; set; }
  public int TimeStamp { get; set; }
  public string Base { get; set; }
  public Dictionary<string, decimal> Rates { get; set; }

Note that property names are not case sensitive, but the name has to exactly match the JSON one. Also, notice how "rates" JSON property is matched to a Dictionary<string, decimal>. If "rates" would have a singular value, they could alternatively be matched to an Array or <code><code>IEnumerable.

Step 3. Create a method to retrieve JSON data and map it to .NET class

Now we will create the following universal method that can be re-used for any .NET class, where 'T' represents any .NET class that you need JSON data to be mapped to:

using System.Net;
using Newtonsoft.Json;

// ...

private static T _download_serialized_json_data<T>(string url) where T : new() {
  using (var w = new WebClient()) {
    var json_data = string.Empty;
    // attempt to download JSON data as a string
    try {
      json_data = w.DownloadString(url);
    catch (Exception) {}
    // if string with JSON data is not empty, deserialize it to class and return its instance 
    return !string.IsNullOrEmpty(json_data) ? JsonConvert.DeserializeObject<T>(json_data) : new T();

Here, at first, an instance of <a href="">WebClient()</a> System.Net class (a part of the .NET) downloads data from the specific URL as a plain string

Then, this string containing JSON data is mapped (deserialized) to any .NET class provided (CurrencyRates in our case). 

Deserialization is done via Json.NET library's method JsonConvert.DeserializeObject<T>(json_data), which attempts to match all JSON fields to the same .NET class fields. 

In this example, a call to a universal method _download_serialized_json_data<T>() can look like this:  

var url = " ";
var currencyRates = _download_serialized_json_data<CurrencyRates>(url); 

(Please note: if you want to use data provided by, first you need to get your unique App Id here:^, than replace YOUR_APP_ID in the sample above.) 

Final Note 

And that's it! Now you can do anything you need with the data you've just retrieved. 

Good luck!



This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Web Developer
United States United States
Coding is awesome!

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Comments and Discussions

Questionreturning null values Pin
Damian Hoffmann15-Sep-16 4:19
memberDamian Hoffmann15-Sep-16 4:19 
PraiseMade Easy? Pin
globalgb15-Nov-15 7:48
memberglobalgb15-Nov-15 7:48 
GeneralMy vote of 5 Pin
GrumpyPants17-Sep-15 9:48
memberGrumpyPants17-Sep-15 9:48 
QuestionJSON Pin
Priyanka Thota23-Jun-15 6:59
memberPriyanka Thota23-Jun-15 6:59 
QuestionHow to handle JSON that has multiple data sets? Pin
Danny MacDonald8-Feb-15 15:02
memberDanny MacDonald8-Feb-15 15:02 
AnswerRe: How to handle JSON that has multiple data sets? Pin
Danny MacDonald8-Feb-15 15:10
memberDanny MacDonald8-Feb-15 15:10 
QuestionMultiple records Pin
Mohsin Mustufa2-Nov-14 7:08
memberMohsin Mustufa2-Nov-14 7:08 
GeneralMy vote of 1 Pin
Dmitry Kirsanov19-Jun-14 6:09
memberDmitry Kirsanov19-Jun-14 6:09 
GeneralMy vote of 5 Pin
Chris8752-Sep-14 3:25
professionalChris8752-Sep-14 3:25 
QuestionHow to access T and iterate Pin
suid00129-May-14 12:57
membersuid00129-May-14 12:57 
AnswerRe: How to access T and iterate Pin
Mikhail-T30-May-14 10:08
memberMikhail-T30-May-14 10:08 
GeneralRe: How to access T and iterate Pin
suid00130-May-14 17:42
membersuid00130-May-14 17:42 
QuestionI got a JsonReaderException Pin
nicocia10-Feb-14 5:06
membernicocia10-Feb-14 5:06 
AnswerRe: I got a JsonReaderException Pin
Mikhail-T10-Feb-14 5:28
memberMikhail-T10-Feb-14 5:28 
GeneralRe: I got a JsonReaderException Pin
nicocia10-Feb-14 5:38
membernicocia10-Feb-14 5:38 
AnswerRe: I got a JsonReaderException Pin
Mikhail-T10-Feb-14 13:06
memberMikhail-T10-Feb-14 13:06 
It took me a while to reply, busy day))

Anyway, the problem is that now Open Exchange Rates requires you to get a unique id (AppID, it's free) to access json data on the site, and url you request latest data from should be like this:

So, instead of json data for the rates, the whole front page of[^] is being downloaded because it redirects there, if no App Id is specified, and of course fails to parse.

To fix your problem:

1. Get your unique App Id here (on free plan):[^]

2. Use extension in this article like this, but with the value of your new App Id (replace YOUR_APP_ID below):
var url = "";
var currencyRates = _download_serialized_json_data<CurrencyRates>(url);

Or see Open Exchange Rates documentation[^] for more details on how to access their API.

Hope that works for you!

GeneralRe: I got a JsonReaderException Pin
nicocia10-Feb-14 22:23
membernicocia10-Feb-14 22:23 
Mikhail Tsennykh18-Jul-13 8:02
memberMikhail Tsennykh18-Jul-13 8:02 
QuestionRe: Use C# to get JSON Data from the Web and Map it to .NET Class => Made Easy! Pin
Omage femi17-May-13 7:46
memberOmage femi17-May-13 7:46 
QuestionTwo minor questions Pin
BillWoodruff30-Apr-13 2:26
memberBillWoodruff30-Apr-13 2:26 
AnswerRe: Two minor questions Pin
Mikhail Tsennykh30-Apr-13 5:43
memberMikhail Tsennykh30-Apr-13 5:43 
Suggestion'Paste JSON As Classes' in Visual Studio Pin
Dave Kerr29-Apr-13 6:24
mvpDave Kerr29-Apr-13 6:24 
GeneralRe: 'Paste JSON As Classes' in Visual Studio Pin
BillWoodruff30-Apr-13 2:23
memberBillWoodruff30-Apr-13 2:23 
GeneralRe: 'Paste JSON As Classes' in Visual Studio Pin
Dave Kerr30-Apr-13 3:17
mvpDave Kerr30-Apr-13 3:17 
GeneralRe: 'Paste JSON As Classes' in Visual Studio Pin
Mikhail Tsennykh30-Apr-13 5:30
memberMikhail Tsennykh30-Apr-13 5:30 

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