Skip to main content

JSON Serialization and De-serialization In Silverlight - Few Handy Extension Methods

This post will give an introduction to JSON, and also I'll share a couple of handy C# extension methods to handle serialization and de-serialization of JSON (Java Script Object Notation) Data. from your Silverlight apps

To know more about JSON format, check out the http://www.json.org - To quote,
JSON (J avaScript Object Notation) is a lightweight data-interchange format. It is easy for humans to read and write. It is easy for machines to parse and generate. These properties make JSON an ideal data-interchange language.

Understanding JSON


In JSON, any object can be serialized to
  • A collection of name/value pairs. (For eg, from C# point of view, a simple example is Dictionary)</STRING,STRING>
  • An ordered list of values. (An array or a list)
JSON is used widely by various web apps, and is ideal for light weight data transfer over REST protocol. For example, Twitter. The following URL gives you the current twitter trends as a JSON string.

URL: http://search.twitter.com/trends/current.json - You may get something like this as reply (I've shortened it a bit :)).

{ "as_of" : 1256965326,
  "trends" : { "2009-10-31 05:02:06" : 
         [ 
          { "name" : "Happy Halloween",
            "query" : "\"Happy Halloween\" OR #Halloween"
          },
          { "name" : "#foofighterslive",
            "query" : "#foofighterslive"
          },
          { "name" : "#Backnthedaycartoon",
            "query" : "#Backnthedaycartoon"
          },
          { "name" : "Follow Friday",
            "query" : "\"Follow Friday\""
          }
        ] }
}

And for your information, here is a quick Online Json Formatter to format your JSON data a bit so that it'll look pretty

JSON In Silverlight


JSON serialization support is provided in Silverlight for long time. Let us have a close look at how an object gets serialized to JSON. Consider a simple Human class.

 public class Human
    {
        public List Children { get; set; }
        public string Name { get; set; }
        public int Age { get; set; }
    }

Let us create a simple Human object and try serializing the same.
  var human = new Human() { Name = "Joe", Age = 10 };

If you serialize the human object using JSON serializer, you'll get something like
{"Age":10,"Children":null,"Name":"Joe"}


You may find that each property/value is represented using a Key Value pair. Now, Let us try with an object graph.
  var human = new Human() 
                { 
                    Name = "Joe", Age = 30 ,
                    Children = new List<Human> 
                    {
                        new Human() {Name="Jim", Age=3},
                        new Human() {Name="July", Age=2}
                    }
                };
And here is the result if you serialize the human object now. Note how the elements in Children collection of human object is serialized and represented in JSON.
{ "Age" : 30,
  "Children" : [ { "Age" : 3,
        "Children" : null,
        "Name" : "Jim"
      },
      { "Age" : 2,
        "Children" : null,
        "Name" : "July"
      }
    ],
  "Name" : "Joe"
}

Serialization and De-Serialization In Silverlight


Now, let us get back to the initial point, how to serialize and deserialize objects to/from JSON in Silverlight? You may use these extension methods I've put together. They are pretty straight forward. The first method adds an extension method to strings for deserializing them, and the second one adds an extension methods to objects for serializing them.
using System;
using System.Runtime.Serialization.Json;
using System.IO;
using System.Text;


namespace JSONHelper
{

    public static class JsonSerializerHelper
    {
        /// <summary>
        /// Adds an extension method to a string
        /// </summary>
        /// <typeparam name="TObj">The expected type of Object</typeparam>
        /// <param name="json">Json string data</param>
        /// <returns>The deserialized object graph</returns>
        public static TObj JsonDeserialize<TObj>(this string json)
        {
            using (MemoryStream mstream = new MemoryStream(Encoding.Unicode.GetBytes(json)))
            {
                DataContractJsonSerializer serializer = 
                         new DataContractJsonSerializer(typeof(TObj));

                return (TObj)serializer.ReadObject(mstream);
            }
        }

        /// <summary>
        /// Serialize the object to Json string
        /// </summary>
        /// <param name="obj">Object to serialize</param>
        /// <returns>Serialized string</returns>
        public static string JsonSerialize(this object obj)
        {
            using (MemoryStream mstream = new MemoryStream())
            {
                DataContractJsonSerializer serializer =
                        new DataContractJsonSerializer(obj.GetType());
                serializer.WriteObject(mstream, obj);
                mstream.Position = 0;

                using (StreamReader reader = new StreamReader(mstream))
                {
                    return reader.ReadToEnd();
                }
            }
        }
    }
}

You may import JSONHelper namespace to use these extension methods, like this. Caution: Please make sure that you've valid JSON string or a serializable object when you use these methods
var human = new Human() 
{ 
    Name = "Joe", Age = 30 ,
    Children = new List 
    {
        new Human() {Name="Jim", Age=3},
        new Human() {Name="July", Age=2}
    }
};

//Serialize the object.
var hstr = human.JsonSerialize();

//Create a cloned object by deserializing the same
var cloned = hstr.JsonDeserialize<Human>();

Alright, that is it for now. Enjoy coding.

 

Shout it

Popular posts from this blog

Top 7 Coding Standards & Guideline Documents For C#/.NET Developers

Some time back, I collated a list of 7 Must Read, Free EBooks for .NET Developers, and a lot of people found it useful. So, I thought about putting together a list of Coding Standard guidelines/checklists for .NET /C# developers as well.As you may already know, it is easy to come up with a document - the key is in implementing these standards in your organization, through methods like internal trainings, Peer Reviews, Check in policies, Automated code review tools etc. You can have a look at FxCop and/or StyleCop for automating the review process to some extent, and can customize the rules based on your requirements.Anyway, here is a list of some good Coding Standard Documents. They are useful not just from a review perspective - going through these documents can definitely help you and me to iron out few hidden glitches we might have in the programming portion of our brain. So, here we go, the listing is not in any specific order.1 – IDesign C# Coding StandardsIDesign C# coding stand…

Creating a quick Todo listing app on Windows using IIS7, Node.js and Mongodb

As I mentioned in my last post, more and more organizations are leaning towards Web Oriented Architecture (WOA) which are highly scalable. If you were exploring cool, scalable options to build highly performing web applications, you know what Node.js is for.After following the recent post from Scott Hanselman, I was up and running quickly with Node.js. In this post, I’ll explain step by step how I’ve setup Node.js and Mongodb to create a simple Todo listing application.Setting up Node.jsThis is what I’ve done.1 – Goto http://nodejs.org/, scroll down and download node.exe for Windows, and place it in your c:\node folder2 – Goto IIS Node project in Git at https://github.com/tjanczuk/iisnode, download the correct ‘retail’ link of IIS Node zip file (I downloaded the already built retail package, otherwise you can download and build from the source).3 – Extract the zip file some where, and run the install.bat or install_iisexpress.bat depending on your IIS Version. If you don’t have IIS in…

5 Awesome Learning Resources For Programmers (To help you and your kids to grow the geek neurons)

Happy New Year, this is my first post in 2012. I’ll be sharing few awesome learning resources I’ve bookmarked, and will be pointing out some specific computer/programming related courses I've found interesting from these resources.Also, thought about saving this blog post for my kids as well - instead of investing in these Child education schemes (though they are too small as of today, 2 years and 60 days respectively ). Anyway, personally my new year resolution is to see as much videos from this course collections (assuming I can find some free time in between my regular job && changing my babies diapers).1 – Khan AcademyAs I mentioned some time back, you and your kids are missing some thing huge if you havn’t heard about Khan Academy.  It is an awesome learning resource, especially if you want to re-visit your basics in Math, Science etc.With a library of over 2,600 videos covering everything from arithmetic to physics, finance, and history and 268 practice exercises, th…