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

Answer 1

Simlpe use of Newtonsoft.Json and Newtonsoft.Json.Linq libraries.

        //Create my object
        var my_jsondata = new
        {
            Host = @"sftp.myhost.gr",
            UserName = "my_username",
            Password = "my_password",
            SourceDir = "/export/zip/mypath/",
            FileName = "my_file.zip"
        };

        //Tranform it to Json object
        string json_data = JsonConvert.SerializeObject(my_jsondata);

        //Print the Json object
        Console.WriteLine(json_data);

        //Parse the json object
        JObject json_object = JObject.Parse(json_data);

        //Print the parsed Json object
        Console.WriteLine((string)json_object["Host"]);
        Console.WriteLine((string)json_object["UserName"]);
        Console.WriteLine((string)json_object["Password"]);
        Console.WriteLine((string)json_object["SourceDir"]);
        Console.WriteLine((string)json_object["FileName"]);

Answer 2

This library is very good for JSON from C#

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

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

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 5

I've found that you don't need the serializer at all. If you return the object as a List. Let me use an example.

In our asmx we get the data using the variable we passed along

// return data
[WebMethod(CacheDuration = 180)]
public List<latlon> GetData(int id) 
{
    var data = from p in db.property 
               where p.id == id 
               select new latlon
               {
                   lat = p.lat,
                   lon = p.lon

               };
    return data.ToList();
}

public class latlon
{
    public string lat { get; set; }
    public string lon { get; set; }
}

Then using jquery we access the service, passing along that variable.

// get latlon
function getlatlon(propertyid) {
var mydata;

$.ajax({
    url: "getData.asmx/GetLatLon",
    type: "POST",
    data: "{'id': '" + propertyid + "'}",
    async: false,
    contentType: "application/json;",
    dataType: "json",
    success: function (data, textStatus, jqXHR) { //
        mydata = data;
    },
    error: function (xmlHttpRequest, textStatus, errorThrown) {
        console.log(xmlHttpRequest.responseText);
        console.log(textStatus);
        console.log(errorThrown);
    }
});
return mydata;
}

// call the function with your data
latlondata = getlatlon(id);

And we get our response.

{"d":[{"__type":"MapData+latlon","lat":"40.7031420","lon":"-80.6047970}]}

Answer 6

This code snippet uses the DataContractJsonSerializer from System.Runtime.Serialization.Json in .NET 3.5.

public static string ToJson<T>(/* this */ T value, Encoding encoding)
{
    var serializer = new DataContractJsonSerializer(typeof(T));

    using (var stream = new MemoryStream())
    {
        using (var writer = JsonReaderWriterFactory.CreateJsonWriter(stream, encoding))
        {
            serializer.WriteObject(writer, value);
        }

        return encoding.GetString(stream.ToArray());
    }
}