How to JSON Serialization and Deserialization in ASP.NET

JSON is one kind of data format which is designer for running JavaScript on website. At present, JSON is widely used in web. This article focuses on JSON Serialization and Deserialization in ASP.NET, including the brief introduction of JSON, how to serialize and deserialize with ASP.NET and operation on date, assembly, dictionary.
1. JSON Brief Introduction
JSON (JavaScript Object Notation) is one ligthweight data exchange format.
JSON is “name/value” assembly. Its structure is made up with {}, [], comma, colon and double quotation marks. And it includes the following data types: Object, Number, Boolean, String, Array, NULL.
JSON has three styles.
Object: An unordered “name/value” assembly. An object begins with “{” and ends with “}”. Behind each “name”, there is a colon. And comma is used to separate much “name/value”. For example:

var user={"name":"Tom","gender":"Male","birthday":"1983-8-8"}

Array: Value ordere set. An array begins with “[” and end with “]”. And values are separated with comma. For example:

var userlist=[{"user":{"name":"Tom","gender":"Male","birthday":"1983-8-8"}},{"user":{"name":"Lucy","gender":"Female","birthday":"1984-7-7"}}]

String: Any quantity unicode character assebly which is enclosed with quotation marks. It uses backlash to escape.
2. Serialize and Deserialize JSON Data
We can use DataContractJsonSerializer to serialize type instance to JSON string and deserialize JSON string to type instance. DataContractJsonSerializer is under System.Runtime.Serialization.Json namespace. It is included in System.ServiceModel.Web.dll in .NET Framework 3.5 and System.Runtime.Serialization in .NET Framework 4.0. We need to add it as reference.
Code for Using DataContractJsonSerialize Serialize and Deserialize

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Runtime.Serialization.Json;
using System.IO;
using System.Text;
/// <summary>
/// JSON Serialization and Deserialization Assistant Class
/// </summary>
public class JsonHelper
{
/// <summary>
/// JSON Serialization
/// </summary>
public static string JsonSerializer<T> (T t)
{
DataContractJsonSerializer ser = new DataContractJsonSerializer(typeof(T));
MemoryStream ms = new MemoryStream();
ser.WriteObject(ms, t);
string jsonString = Encoding.UTF8.GetString(ms.ToArray());
ms.Close();
return jsonString;
}
/// <summary>
/// JSON Deserialization
/// </summary>
public static T JsonDeserialize<T> (string jsonString)
{
DataContractJsonSerializer ser = new DataContractJsonSerializer(typeof(T));
MemoryStream ms = new MemoryStream(Encoding.UTF8.GetBytes(jsonString));
T obj = (T)ser.ReadObject(ms);
return obj;
}
}

Serialization Demo:
Simple Object Person:

public class Person
{
public string Name { get; set; }
public int Age { get; set; }
}
Serialize as JSON String:
protected void Page_Load(object sender, EventArgs e)
{
Person p = new Person();
p.Name = "Tom";
p.Age = 28;
string jsonString = JsonHelper.JsonSerializer<person>(p);
Response.Write(jsonString);
}
</person>


Result:

{"Age":28,"Name":"Tom"}

Reserialization Demo:


protected void Page_Load(object sender, EventArgs e)
{
string jsonString = "{"Age":28,"Name":"Tom"}";
Person p = JsonHelper.JsonDeserialize<person>(jsonString);
}
</person>


In ASP.NET, JSON serializaation and deserialization can use JavaScriptSerializer which is under System.Web.Script.Serialization namespace. We need to add System.Web.Extensions.dll as reference or use JSON.NET.
3. JSON Serialization and Deserialization on DateTime
JSON cannot support date and time directly. The value of DateTime is shown as “/Date(700000+0500)/”. The first number (700000) stands for milliseconds from Jan. 1, 1970 according to base time (not saylight saving time) in GMT. The number can be negative to present time before Jan. 1, 1970. The part “+0500” is optional. It present the time is Local, in other words, it can be converted to local time zone when deserializing. If there is no this part, the time will be deserialized as UTC.
Modify Person and add LastLoginTime:


public class Person
{
public string Name { get; set; }
public int Age { get; set; }
public DateTime LastLoginTime { get; set; }
}
Person p = new Person();
p.Name = "Tom";
p.Age = 28;
p.LastLoginTime = DateTime.Now;
string jsonString = JsonHelper.JsonSerializer<person>(p);
</person>


Result of Serialization:

{"Age":28,"LastLoginTime":"/Date(1319266795390+0800)/","Name":"Tom"}

I. Replace it with regular expression on background and modify JsonHelper:


using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Runtime.Serialization.Json;
using System.IO;
using System.Text;
using System.Text.RegularExpressions;
/// <summary>
/// JSON Serialization and Deserialization Assistant Class
/// </summary>
public class JsonHelper
{
/// <summary>
/// JSON Serialization
/// </summary>
public static string JsonSerializer(T t)
{
DataContractJsonSerializer ser = new DataContractJsonSerializer(typeof(T));
MemoryStream ms = new MemoryStream();
ser.WriteObject(ms, t);
string jsonString = Encoding.UTF8.GetString(ms.ToArray());
ms.Close();
//Replace Json Date String
string p = @”\/Date((d+)+d+)\/”;
MatchEvaluator matchEvaluator = new MatchEvaluator(ConvertJsonDateToDateString);
Regex reg = new Regex(p);
jsonString = reg.Replace(jsonString, matchEvaluator);
return jsonString;
}
/// <summary>
/// JSON Deserialization
/// </summary>
public static T JsonDeserialize(string jsonString)
{
//Convert “yyyy-MM-dd HH:mm:ss” String as “/Date(1319266795390+0800)/”
string p = @”d{4}-d{2}-d{2}sd{2}:d{2}:d{2}”;
MatchEvaluator matchEvaluator = new MatchEvaluator(ConvertDateStringToJsonDate);
Regex reg = new Regex(p);
jsonString = reg.Replace(jsonString, matchEvaluator);
DataContractJsonSerializer ser = new DataContractJsonSerializer(typeof(T));
MemoryStream ms = new MemoryStream(Encoding.UTF8.GetBytes(jsonString));
T obj = (T)ser.ReadObject(ms);
return obj;
}
/// <summary>
/// Convert Serialization Time /Date(1319266795390+0800) as String
/// </summary>
private static string ConvertJsonDateToDateString(Match m)
{
string result = string.Empty;
DateTime dt = new DateTime(1970,1,1);
dt = dt.AddMilliseconds(long.Parse(m.Groups[1].Value));
dt = dt.ToLocalTime();
result = dt.ToString(“yyyy-MM-dd HH:mm:ss”);
return result;
}
/// <summary>
/// Convert Date String as Json Time
/// </summary>
private static string ConvertDateStringToJsonDate(Match m)
{
string result = string.Empty;
DateTime dt = DateTime.Parse(m.Groups[0].Value);
dt = dt.ToUniversalTime();
TimeSpan ts = dt – DateTime.Parse(“1970-01-01”);
result = string.Format(“\/Date({0}+0800)\/”,ts.TotalMilliseconds);
return result;
}
}

Serialization Demo:


Person p = new Person();
p.Name = "Tom";
p.Age = 28;
p.LastLoginTime = DateTime.Now;
string jsonString = JsonHelper.JsonSerializer<person>(p);
</person>


Result:

{"Age":28,"LastLoginTime":"2011-10-22 14:55:00","Name":"Tom"}

Deserialization Demo:

string json = "{"Age":28,"LastLoginTime":"2011-10-22 14:55:00","Name":"Tom"}";
p=JsonHelper.JsonDeserialize<person>(json);
</person>

Result:
II. Use JaveScript:


function ChangeDateFormat(jsondate) {
jsondate = jsondate.replace("/Date(", "").replace(")/", "");
if (jsondate.indexOf("+") > 0) {
jsondate = jsondate.substring(0, jsondate.indexOf("+"));
}
else if (jsondate.indexOf("-") > 0) {
jsondate = jsondate.substring(0, jsondate.indexOf("-"));
}
var date = new Date(parseInt(jsondate, 10));
var month = date.getMonth() + 1 < 10 ? "0" + (date.getMonth() + 1) : date.getMonth() + 1;
var currentDate = date.getDate() < 10 ? "0" + date.getDate() : date.getDate();
return date.getFullYear() + "-" + month + "-" + currentDate;
}

Simple Demo:

ChangeDateFormat("/Date(1319266795390+0800)/");

Result:

2011-10-22 14:55:00

4. JSON Serialization and Deserialization Assembly, Dictionary and Array Disposition
In JSON data, all the assemblies, dictionaries and arrays are presented as array.
List Serialization:


List<person> list = new List<person>()
{
new Person(){ Name="Tom", Age=28},
new Person(){ Name="Lucy", Age=27}
};
string jsonString = JsonHelper.JsonSerializer<list<person>>(list);
</list<person></person></person>

Serialization Result:

"[{"Age":28,"Name":"Tom"},{"Age":27,"Name":"Lucy"}]" <

Dictionary cannot be used in JSON directly. If we want to convert Dictionary to JSON, we should take Key of Dictionary as value of name “Key and Value of Dictionary as value of “Value”. For example:

Dictionary<string,> dic = new Dictionary<string,>();
dic.Add("Name", "Tom");
dic.Add("Age", "28");
string jsonString = JsonHelper.JsonSerializer < Dictionary<string,>>(dic);
</string,></string,></string,>

Serialization Result:

"[{"Key":"Name","Value":"Tom"},{"Key":"Age","Value":"28"}]"

Reference:
JSON: http://www.json.org/
Stand-Alone JSON Serialization: http://msdn.microsoft.com/en-us/library/bb412170.aspx
Serialize and Deserialize JSON Data: http://msdn.microsoft.com/en-us/library/bb412179.aspx
JSON Serialize and Deserialize : http://www.codeproject.com/KB/aspnet/Seria_Deseria_ASP_NET.aspx