How to create JSON string in C#

Question

I just used the XmlWriter to create some XML to send back in an HTTP response. How would you create a JSON string. I assume you would just use a stringbuilder to build the JSON string and them format your response as JSON?

Answer 1

Encode Usage

Simple object to JSON Array EncodeJsObjectArray()

public class dummyObject
{
    public string fake { get; set; }
    public int id { get; set; }

    public dummyObject()
    {
        fake = "dummy";
        id = 5;
    }

    public override string ToString()
    {
        StringBuilder sb = new StringBuilder();
        sb.Append('[');
        sb.Append(id);
        sb.Append(',');
        sb.Append(JSONEncoders.EncodeJsString(fake));
        sb.Append(']');

        return sb.ToString();
    }
}

dummyObject[] dummys = new dummyObject[2];
dummys[0] = new dummyObject();
dummys[1] = new dummyObject();

dummys[0].fake = "mike";
dummys[0].id = 29;

string result = JSONEncoders.EncodeJsObjectArray(dummys);

Result: [[29,"mike"],[5,"dummy"]]

Pretty Usage

Pretty print JSON Array PrettyPrintJson() string extension method

string input = "[14,4,[14,\"data\"],[[5,\"10.186.122.15\"],[6,\"10.186.122.16\"]]]";
string result = input.PrettyPrintJson();

Results is:

[
   14,
   4,
   [
      14,
      "data"
   ],
   [
      [
         5,
         "10.186.122.15"
      ],
      [
         6,
         "10.186.122.16"
      ]
   ]
]

Answer 2

If you can't or don't want to use the two built-in JSON serializers (JavaScriptSerializer and DataContractJsonSerializer) you can try the JsonExSerializer library - I use it in a number of projects and works quite well.

Answer 3

If you're trying to create a web service to serve data over JSON to a web page, consider using the ASP.NET Ajax toolkit:

http://www.asp.net/learn/ajax/tutorial-05-cs.aspx

It will automatically convert your objects served over a webservice to json, and create the proxy class that you can use to connect to it.

Answer 4

This library is very good for JSON from C#

http://james.newtonking.com/pages/json-net.aspx

Answer 5

You can also try my ServiceStack JsonSerializer it's the fastest .NET JSON serializer at the moment. It supports serializing DataContracts, any POCO Type, Interfaces, Late-bound objects including anonymous types, etc.

Basic Example

var customer = new Customer { Name="Joe Bloggs", Age=31 };
var json = JsonSerializer.SerializeToString(customer);
var fromJson = JsonSerializer.DeserializeFromString<Customer>(json); 

Note: Only use Microsofts JavaScriptSerializer if performance is not important to you as I've had to leave it out of my benchmarks since its up to 40x-100x slower than the other JSON serializers.

Answer 6

You could use the JavaScriptSerializer class, check this article to build an useful extension method.

Code from article:

namespace ExtensionMethods
{
    public static class JSONHelper
    {
        public static string ToJSON(this object obj)
        {
            JavaScriptSerializer serializer = new JavaScriptSerializer();
            return serializer.Serialize(obj);
        }

        public static string ToJSON(this object obj, int recursionDepth)
        {
            JavaScriptSerializer serializer = new JavaScriptSerializer();
            serializer.RecursionLimit = recursionDepth;
            return serializer.Serialize(obj);
        }
    }
}

Usage:

using ExtensionMethods;

...

List<Person> people = new List<Person>{
                   new Person{ID = 1, FirstName = "Scott", LastName = "Gurthie"},
                   new Person{ID = 2, FirstName = "Bill", LastName = "Gates"}
                   };


string jsonString = people.ToJSON();